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A355941
Numbers k such that A003973(k) is a multiple of A000203(k).
3
1, 6, 14, 15, 24, 35, 42, 56, 105, 168, 210, 286, 376, 470, 552, 637, 672, 715, 840, 858, 874, 969, 1144, 1274, 1288, 1410, 1848, 1880, 2001, 2002, 2145, 2185, 2261, 2622, 3021, 3185, 3290, 3296, 3375, 3432, 3496, 3822, 4290, 4669, 4830, 4968, 5005, 5096, 5640, 6118, 6291, 6555, 6783, 7049, 7776, 8008, 9555, 9888
OFFSET
1,2
COMMENTS
If both x and y are terms and gcd(x, y) = 1, then x*y is a term also.
MATHEMATICA
f[p_, e_] := ((q = NextPrime[p])^(e + 1) - 1)/(q - 1); Select[Range[10^4], # == 1 || Divisible[Times @@ f @@@ FactorInteger[#], DivisorSigma[1, #]] &] (* Amiram Eldar, Jul 22 2022 *)
PROG
(PARI)
A003973(n) = { my(f = factor(n)); for(i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); sigma(factorback(f)); };
A355940(n) = !(A003973(n)%sigma(n));
isA355941(n) = A355940(n);
CROSSREFS
Positions of 1's in A355934, and also in A355940 (characteristic function).
Sequence in context: A107982 A341448 A081535 * A359912 A325698 A338907
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jul 22 2022
STATUS
approved