OFFSET
1,5
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
FORMULA
MAPLE
A170825 := proc(n) a := 1 ; for p in numtheory[factorset](n) do if p mod 6 = 5 then a := a*p ; end if ; end do ; a ; end proc: seq(A170825(n), n=1..120) ; # R. J. Mathar, Jan 21 2010
MATHEMATICA
Table[Times@@Select[Transpose[FactorInteger[n]][[1]], IntegerQ[(#+1)/6]&], {n, 100}] (* Harvey P. Dale, Nov 01 2013 *)
PROG
(PARI) a(n) = my(f=factor(n)); for(i=1, #f~, f[i, 2] = (f[i, 1]%6)==5); factorback(f); \\ Michel Marcus, Sep 30 2020
CROSSREFS
KEYWORD
nonn,mult,easy
AUTHOR
N. J. A. Sloane, Dec 25 2009, following a suggestion from Jonathan Vos Post
EXTENSIONS
More terms from R. J. Mathar, Jan 21 2010
STATUS
approved