A374196 a(n) is the minimum value of A017666 that it obtains among divisors of n larger than 1. By convention a(1) = 1.

1, 2, 3, 2, 5, 1, 7, 2, 3, 2, 11, 1, 13, 2, 3, 2, 17, 1, 19, 2, 3, 2, 23, 1, 5, 2, 3, 1, 29, 1, 31, 2, 3, 2, 5, 1, 37, 2, 3, 2, 41, 1, 43, 2, 3, 2, 47, 1, 7, 2, 3, 2, 53, 1, 5, 1, 3, 2, 59, 1, 61, 2, 3, 2, 5, 1, 67, 2, 3, 2, 71, 1, 73, 2, 3, 2, 7, 1, 79, 2, 3, 2, 83, 1, 5, 2, 3, 2, 89, 1, 7, 2, 3, 2, 5, 1, 97, 2, 3, 2

Offset: 1

Author

Antti Karttunen, Jul 07 2024

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 1..100000
• Index entries for sequences related to sigma(n)

Crossrefs

Cf. A000203, A017666, A374198 (indices of 1's in this sequence).

Cf. also A374204.

Programs

PARI

A374196(n) = { my(m=0,x); fordiv(n,d,if(d>1, x = denominator(sigma(d)/d); if(!m || x
				

Formula

a(1) = 1, and for n > 1, a(n) = Min_{d|n, d>1} A017666(d).