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A336552
Numbers k such that A003557(k)-1 either divides A326143(k) [= A001065(k) - A007947(k)], or both are zero. Numbers k such that gcd(A336551(k), A326143(k)) is equal to A336551(k).
3
4, 6, 12, 20, 24, 28, 44, 45, 48, 52, 60, 63, 68, 76, 84, 90, 92, 96, 99, 116, 117, 120, 124, 126, 132, 140, 144, 147, 148, 150, 153, 156, 164, 168, 171, 172, 188, 192, 198, 204, 207, 212, 220, 228, 234, 236, 244, 260, 261, 264, 268, 272, 276, 279, 284, 292, 294, 306, 308, 312, 315, 316, 325, 332, 333, 340, 342, 348, 350
OFFSET
1,1
COMMENTS
Numbers k such that either A336551(k) and A326143(k) are both zero (in which case k is squarefree), or A336551(k) divides A326143(k) (in which case k is not squarefree).
LINKS
PROG
(PARI)
A007947(n) = factorback(factorint(n)[, 1]);
A326143(n) = (sigma(n)-A007947(n)-n);
A336551(n) = { my(f=factor(n)); for(i=1, #f~, f[i, 2] = f[i, 2]-1); (factorback(f)-1); };
isA336552(n) = { my(u=A336551(n)); (u==gcd(u, A326143(n))); };
CROSSREFS
Cf. A007947, A326143, A336550, A336551, A336553 (odd terms).
Sequence in context: A306270 A045956 A057339 * A160856 A019445 A119638
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jul 28 2020
STATUS
approved