A363316 Sum of divisors of 4*n-2 of form 4*k+1.
1, 1, 6, 1, 10, 1, 14, 6, 18, 1, 22, 1, 31, 10, 30, 1, 34, 6, 38, 14, 42, 1, 60, 1, 50, 18, 54, 6, 58, 1, 62, 31, 84, 1, 70, 1, 74, 31, 78, 1, 91, 1, 108, 30, 90, 14, 94, 6, 98, 43, 102, 1, 132, 1, 110, 38, 114, 6, 140, 18, 122, 42, 156, 1, 130, 1, 134, 60, 138, 1, 142, 14, 180, 71, 150, 1, 180, 6, 158, 54
Offset: 1
Keywords
Programs
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Mathematica
a[n_] := DivisorSum[4*n - 2, # &, Mod[#, 4] == 1 &]; Array[a, 100] (* Amiram Eldar, Jul 08 2023 *)
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PARI
a(n) = sumdiv(4*n-2, d, (d%4==1)*d);
Formula
a(n) = A050449(4*n-2).
G.f.: Sum_{k>0} (4*k-3) * x^(2*k-1) / (1 - x^(4*k-3)).