A379479 Numbers k such that the greatest common divisor of k, sigma(k) and A003961(k) is 1 and gcd(A003961(k)-2k, A003961(k)-sigma(k)) > 1.

7, 13, 19, 28, 31, 37, 43, 46, 55, 61, 67, 68, 69, 79, 91, 97, 103, 106, 109, 127, 131, 139, 146, 151, 163, 166, 175, 181, 193, 199, 200, 223, 229, 241, 251, 261, 271, 277, 283, 301, 307, 313, 323, 325, 331, 337, 344, 346, 349, 371, 379, 391, 397, 409, 421, 428, 439, 444, 449, 457, 463, 466, 475, 481, 487, 491, 494, 496

Offset: 1

Author

Antti Karttunen, Dec 23 2024

Keywords

• nonn

Comments

Not a subsequence of A319630. Terms 175, 323, 444, 847, 874, 1095, 1147, 1236, 1400, 1573, 1768, 1884, 2001, ... are instead in A104210.

Examples

			7 is included as the greatest common divisor of 7, 8 and 9 is 1, but the greatest common divisor of 11-14 and 11-8 is 3 > 1.
28 is included as the greatest common divisor of 28, 56 and 99 is 1, but gcd(99-56,99-56) = 43 > 1.
		

Links

• Antti Karttunen, Table of n, a(n) for n = 1..20000
• Index entries for sequences related to prime indices in the factorization of n.
• Index entries for sequences related to sigma(n).

Crossrefs

Setwise difference A379477 \ A372566.

Cf. A000203, A003961, A326057, A372565, A379478 (characteristic function).

Cf. A000396 (at least the even terms > 6 form a subsequence of this sequence).

Cf. also A104210, A319630.

Programs

PARI

is_A379479 = A379478;

Formula

{k such that A372565(k) = 1 and A326057(k) > 1}.