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Search: a046339 -id:a046339
Displaying 1-4 of 4 results found. page 1
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A163178 a(n) is the central prime factor of A046339(n). +20
1
2, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 5, 2, 3, 3, 2, 5, 2, 5, 2, 3, 2, 2, 7, 3, 3, 5, 3, 5, 2, 3, 2, 3, 2, 2, 5, 2, 5, 3, 7, 2, 3, 7, 3, 2, 5, 2, 5, 3, 2, 3, 5, 2, 3, 7, 3, 2, 5, 2, 5, 2, 3, 2, 2, 3, 5, 7, 2, 7, 11, 3, 2, 7, 3, 3, 5, 3, 3, 2, 7, 2, 3, 2, 7, 5, 3, 2, 3, 2, 5, 11, 2, 5, 2, 3, 2, 5, 2, 2, 3, 2, 7, 5 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
Table of n, a(n) for n=1..104.
EXAMPLE
a(8)=2 since A046339(8) = 32 = 2*2*2*2*2.
a(9)=3 since A046339(9) = 42 = 2*3*7.
a(10)=2 since A046339(10) = 44 = 2*2*11.
a(11)=3 since A046339(11) = 45 = 3*3*5.
a(12)=2 since A046339(12) = 48 = 2*2*2*2*3.
MAPLE
cpr := proc(n) nred := n ; while numtheory[bigomega](nred) > 1 do pf := sort(convert(numtheory[factorset](nred), list)) ; nred := nred/op(1, pf)/op(-1, pf) ; od: nred ; end:
A046339 := proc(n) option remember ; if n = 1 then 8 ; else for a from procname(n-1)+1 do if not isprime(a) and numtheory[bigomega](a) mod 2 = 1 then RETURN(a) ; fi; od: fi; end:
A163178 := proc(n) cpr(A046339(n)) ; end; seq(A163178(n), n=1..120) ; # R. J. Mathar, Jul 25 2009
CROSSREFS
Cf. A046339, A162361.
KEYWORD
nonn
AUTHOR
Juri-Stepan Gerasimov, Jul 22 2009
EXTENSIONS
More terms from R. J. Mathar, Jul 25 2009
STATUS
approved
A067537 Duplicate of A046339. +20
0
8, 12, 18, 20, 27, 28, 30, 32, 42, 44, 45, 48, 50, 52, 63, 66, 68, 70, 72, 75, 76, 78, 80 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,1
LINKS
Table of n, a(n) for n=0..22.
KEYWORD
dead
STATUS
approved
A046340 Odd composite numbers with an odd number of prime factors (counted with multiplicity). +10
4
27, 45, 63, 75, 99, 105, 117, 125, 147, 153, 165, 171, 175, 195, 207, 231, 243, 245, 255, 261, 273, 275, 279, 285, 325, 333, 343, 345, 357, 363, 369, 385, 387, 399, 405, 423, 425, 429, 435, 455, 465, 475, 477, 483, 507, 531, 539, 549, 555, 561, 567, 575 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
John Cerkan, Table of n, a(n) for n = 1..10000
MATHEMATICA
Select[Range[3, 699, 2], OddQ[Total[Transpose[FactorInteger[#]][[2]]]] && !PrimeQ[#]&] (* Harvey P. Dale, Dec 09 2010 *)
Select[Range[3, 699, 2], CompositeQ[#]&&OddQ[PrimeOmega[#]]&] (* Harvey P. Dale, Jun 18 2024 *)
CROSSREFS
Cf. A046339, A046341.
KEYWORD
nonn
AUTHOR
Patrick De Geest, Jun 15 1998
EXTENSIONS
Name (description) modified by Harvey P. Dale, Dec 09 2010
STATUS
approved
A046341 Composite palindromes with an odd number of prime factors (counted with multiplicity). +10
3
8, 44, 66, 99, 171, 212, 222, 242, 252, 272, 282, 292, 333, 343, 363, 404, 434, 464, 474, 494, 555, 575, 595, 606, 616, 646, 656, 696, 747, 777, 828, 848, 888, 909, 969, 1001, 1221, 1331, 1551, 1771, 2222, 2552, 2882, 3333, 3553, 4004, 4224, 4334, 4554 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
John Cerkan, Table of n, a(n) for n = 1..10000
CROSSREFS
Cf. A046339, A046340.
KEYWORD
nonn,base
AUTHOR
Patrick De Geest, Jun 15 1998
EXTENSIONS
Title corrected by Sean A. Irvine, Apr 08 2021
STATUS
approved
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Last modified September 13 05:52 EDT 2024. Contains 375859 sequences. (Running on oeis4.)