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A351575
Positions of primes in A351568.
2
4, 9, 12, 16, 18, 20, 25, 28, 44, 45, 48, 50, 52, 60, 63, 64, 68, 72, 75, 76, 80, 84, 90, 92, 99, 108, 112, 116, 117, 124, 126, 132, 140, 148, 150, 153, 156, 164, 171, 172, 175, 176, 188, 192, 198, 200, 204, 207, 208, 212, 220, 228, 234, 236, 240, 244, 260, 261, 268, 272, 275, 276, 279, 284, 288, 289, 292, 304, 306
OFFSET
1,1
COMMENTS
Numbers k such that A350388(k) is one of the terms of A023194.
MATHEMATICA
f[p_, e_] := If[EvenQ[e], (p^(e + 1) - 1)/(p - 1), 1]; s[1] = 1; s[n_] := Times @@ f @@@ FactorInteger[n]; Select[Range[300], PrimeQ[s[#]] &] (* Amiram Eldar, Feb 25 2022 *)
PROG
(PARI)
A350388(n) = { my(m=1, f=factor(n)); for(k=1, #f~, if(0==(f[k, 2]%2), m *= (f[k, 1]^f[k, 2]))); (m); };
A351568(n) = sigma(A350388(n));
isA351575(n) = isprime(A351568(n));
CROSSREFS
Positions of primes in A351568, positions of ones in A351570.
Sequence in context: A374904 A162645 A377816 * A348739 A135572 A337103
KEYWORD
nonn
AUTHOR
Antti Karttunen, Feb 24 2022
STATUS
approved