A379230 Difference A003961(k)-(2*k) computed for the natural numbers k for which gcd(k,A003961(k)) > 1, where A003961 is fully multiplicative with a(prime(i)) = prime(i+1).

3, 21, 5, 39, 87, 45, 7, 153, 81, 85, 309, 267, 195, 63, 91, 531, 95, -11, 99, 327, 345, 1023, 81, 175, 909, 117, 705, 573, 321, 605, 159, 413, -65, 1737, 435, 121, 453, 1551, 125, 1149, 117, 189, 1215, 183, 3261, 205, 579, 447, 735, 2943, -119, 171, 775, 579, 253, 807, 2355, 357, 153, 1971, 155, 189, 1227, 2085

Offset: 1

Author

Antti Karttunen, Dec 22 2024

Keywords

• sign

Comments

Each of the primes 3, 5, 7 occur here just once, while some other primes may occur multiple times, although very rare in general. See A379231 and A379232.

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.

Crossrefs

Cf. A104210, A252748.

Cf. A379231 (terms whose absolute value is a prime), A379232 (corresponding terms of A104210).

Cf. also A379233, A379235, A379237.

Formula

a(n) = A252748(A104210(n)).