A367506 a(n) = Sum_{d|n} (d+n)^n.
2, 25, 280, 6017, 107776, 3897218, 107510656, 4867995713, 204519070720, 10904505179450, 585061309782016, 38168392129581810, 2481946587976990720, 185404290282527361386, 14389574562121084305408, 1221867855128546542385409, 108430221517525671050739712
Offset: 1
Keywords
Programs
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PARI
a(n) = sumdiv(n, d, (d+n)^n);
Formula
a(n) = Sum_{k=0..n} n^(n-k) * binomial(n,k) * sigma_k(n).