A367507 a(n) = Sum_{d|n} (d+2)^n.
3, 25, 152, 1633, 17050, 282594, 4785156, 101751713, 2359920499, 62200947098, 1792160571184, 56765070083650, 1946195069953698, 72080471103601322, 2862427829603252768, 121449533922042173249, 5480386857784931326102, 262149577935595805876315
Offset: 1
Keywords
Programs
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PARI
a(n) = sumdiv(n, d, (d+2)^n);
Formula
a(n) = Sum_{k=0..n} 2^(n-k) * binomial(n,k) * sigma_k(n).