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A341016
Numbers k such that A124440(k) is a multiple of A066840(k).
1
2, 3, 4, 6, 8, 10, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60, 64, 68, 72, 76, 80, 84, 88, 92, 96, 100, 104, 108, 112, 116, 120, 124, 128, 132, 136, 140, 144, 148, 152, 156, 160, 164, 168, 172, 176, 180, 184, 188, 192, 196, 200, 204, 208, 212, 216, 220, 224, 228, 232, 236, 240, 244
OFFSET
1,1
COMMENTS
Numbers k such that k*A000010(k)/2 is a multiple of A066840(k).
Includes all multiples of 4.
Are 2, 3, 6 and 10 the only terms that are not multiples of 4?
LINKS
MAPLE
N:= 1000: # for terms <= N
G:= add(numtheory:-mobius(n)*n*x^(2*n)/((1-x^n)*(1-x^(2*n))^2), n=1..N/2):
S:= series(G, x, N+1):
A66840:= [seq(coeff(S, x, j), j=1..N)]:
filter:= n -> n*numtheory:-phi(n)/2 mod A66840[n] = 0:
select(filter, [$2..N]);
CROSSREFS
KEYWORD
nonn
AUTHOR
J. M. Bergot and Robert Israel, Feb 02 2021
STATUS
approved