A065805 - OEIS

%I #16 Sep 13 2018 04:16:43

%S 2,10,44,377,3912,57214,960808,19261862,435877584,11123320200,

%T 313842837684,9729290348250,328114698808288,11967567841654610,

%U 469172063576559648,19676848703371278527,878942778254232811956

%N a(n) = Sum_{j=0..n} sigma(j,n).

%C PARI calls it sigma(n, j). - _Harry J. Smith_, Oct 31 2009

%H Harry J. Smith, <a href="/A065805/b065805.txt">Table of n, a(n) for n = 1..100</a>

%F a(n) ~ n^(n+1) / (n-1). - _Vaclav Kotesovec_, Sep 11 2018

%e n=6; a(6) = 4 + 12 + 50 + 252 + 1394 + 8052 + 47450 = 57214.

%t a[ n ]=Table[ Apply[ Plus, Table[ DivisorSigma[ w, n ], {w, 0, n} ] ].

%o (PARI) { for (n=1, 100, a=sum(j=0, n, sigma(n, j)); write("b065805.txt", n, " ", a) ) } \\ _Harry J. Smith_, Oct 31 2009

%Y Cf. A000005, A000203, A001157, A319194.

%K nonn

%O 1,1

%A _Labos Elemer_, Nov 21 2001