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).

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

Antti Karttunen, Table of n, a(n) for n = 1..10000

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

Adjacent sequences: A336549 A336550 A336551 * A336553 A336554 A336555

Keyword

nonn

Author

Antti Karttunen, Jul 28 2020

Status

approved