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%I #10 Aug 16 2019 07:52:55
%S 1,4,10,27,73,227,767,2860,11569,50363,234155,1156037,6031747,
%T 33130183,190929773,1151198266,7243777228,47462906925,323188163747,
%U 2282922216815,16701529748617,126359471558611,987316752551411,7957198067362137
%N a(n) = Sum{k=1 to n} sigma_{n-k+1}(k), where sigma_m(k) = sum{j|k} j^m.
%e a(5) = 1^5 + (1^4 +2^4) + (1^3 +3^3) + (1^2 +2^2 +4^2) + (1^1 +5^1) = 1 + 17 + 28 + 21 + 6 = 73.
%p with(numtheory): s:=proc(n,k) local div: div:=divisors(n): sum(div[j]^k,j=1..tau(n)) end: a:=n->sum(s(i,n-i+1),i=1..n): seq(a(n),n=1..25); # _Emeric Deutsch_, Jul 13 2005
%o (PARI) a(n) = sum(k=1, n, sigma(k, n-k+1)); \\ _Michel Marcus_, Aug 16 2019
%Y Cf. A108699 (with product).
%K nonn
%O 1,2
%A _Leroy Quet_, Jul 07 2005
%E More terms from _Emeric Deutsch_, Jul 13 2005
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