A221951 Number of subgroups of C_4 X C_n.
3, 8, 6, 15, 6, 16, 6, 22, 9, 16, 6, 30, 6, 16, 12, 29, 6, 24, 6, 30, 12, 16, 6, 44, 9, 16, 12, 30, 6, 32, 6, 36, 12, 16, 12, 45, 6, 16, 12, 44, 6, 32, 6, 30, 18, 16, 6, 58, 9, 24, 12, 30, 6, 32, 12, 44, 12, 16, 6, 60, 6, 16, 18, 43, 12, 32, 6, 30, 12, 32, 6, 66, 6, 16, 18, 30, 12, 32, 6, 58
Offset: 1
Keywords
Links
- Antti Karttunen, Table of n, a(n) for n = 1..65537
Programs
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PARI
A221951(n) = sumdiv(n,d,(1+gcd(2,d)+gcd(4,d))); \\ Antti Karttunen, Sep 30 2018
Formula
a(n) = Sum_{d|n} (1+gcd(2,d)+gcd(4,d)). - Antti Karttunen, Sep 30 2018