A140213 Product_{h|n and h mod 6 = 1} h; product of divisors of n of the form 6*k + 1.

1, 1, 1, 1, 1, 1, 7, 1, 1, 1, 1, 1, 13, 7, 1, 1, 1, 1, 19, 1, 7, 1, 1, 1, 25, 13, 1, 7, 1, 1, 31, 1, 1, 1, 7, 1, 37, 19, 13, 1, 1, 7, 43, 1, 1, 1, 1, 1, 343, 25, 1, 13, 1, 1, 55, 7, 19, 1, 1, 1, 61, 31, 7, 1, 13, 1, 67, 1, 1, 7, 1, 1, 73, 37, 25, 19, 7, 13, 79, 1, 1, 1, 1, 7, 85, 43, 1, 1, 1, 1, 8281

Offset

1,7

Links

Antti Karttunen, Table of n, a(n) for n = 1..10001

Maple

A140213 := proc(n)
    a := 1;
    for d in numtheory[divisors](n) do
        if modp(d, 6) = 1 then
            a := a*d ;
        end if;
    end do:
    a;
end proc: # R. J. Mathar, Dec 15 2015

Prog

(PARI) A140213(n) = { my(m=1); fordiv(n, d, if(1==(d%6), m *= d)); (m); }; \\ Antti Karttunen, Jul 09 2017

Crossrefs

Cf. A170824, A248909, A279060.

Sequence in context: A240831 A170824 A248909 * A331927 A285483 A284097

Adjacent sequences: A140210 A140211 A140212 * A140214 A140215 A140216

Keyword

nonn,easy,look

Author

R. J. Mathar, Jun 27 2008

Extensions

More terms from D. S. McNeil, Mar 24 2009

Status

approved