A363317 - OEIS

%I #13 Jul 08 2023 08:05:02

%S 1,6,10,14,18,22,31,30,34,38,42,60,50,54,58,62,84,70,74,78,91,108,90,

%T 94,98,102,132,110,114,140,122,156,130,134,138,142,180,150,180,158,

%U 162,204,183,174,178,182,228,220,194,198,202,252,210,214,218,252,310,230,234,238,242,300,250,254,258,300,324

%N Sum of divisors of 4*n-3 of form 4*k+1.

%F a(n) = A050449(4*n-3).

%F G.f.: Sum_{k>0} (4*k-3) * x^k / (1 - x^(4*k-3)).

%t a[n_] := DivisorSum[4*n - 3, # &, Mod[#, 4] == 1 &]; Array[a, 100] (* _Amiram Eldar_, Jul 08 2023 *)

%o (PARI) a(n) = sumdiv(4*n-3, d, (d%4==1)*d);

%Y Cf. A050449, A359227, A364083.

%K nonn

%O 1,2

%A _Seiichi Manyama_, Jul 08 2023