OFFSET
1,2
COMMENTS
If n is a 3-smooth number, (i.e. of form 2^i*3^j for i,j>=0) the value c(n,k)={(n^(2k)-1)*B(2k)} is independent of k where {x} denotes the fractional part of x and B(k) is the k-th Bernoulli's number.
FORMULA
a(1)=0; for k>0, a(2^k)=3 a(3^k)=2; for i>0 and j>0 a(2^i*3^j)=5
PROG
(PARI) m=7; for(n=1, 1000000, if(gcd(n, 6^100)==n, print1(6*frac((n^(2*m)-1)*bernfrac(2*m)), ", ")))
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Oct 25 2004
STATUS
approved