A036782 - OEIS

%I #23 Jan 15 2021 07:43:00

%S 0,2,5,12,37,158,879,5920,46241,409122,4037923,43954724,522956325,

%T 6749977126,93928268327,1401602636328,22324392524329,378011820620330,

%U 6780385526348331,128425485935180332,2561327494111820333

%N a(n) = n - 1 + Sum_{j=0..n} j!.

%F a(n) = A036781(n) - 1.

%F E.g.f.: exp(x-1)*(Ei(1)-Ei(1-x)) + exp(x)*(x-1) + 1/(1-x). - _Robert Israel_, Jan 05 2015

%p N:= 30: # to get a(0) to a(N)

%p C:= ListTools:-PartialSums([seq(j!,j=0..N)]):

%p seq(n-1+C[n+1],n=0..N); # _Robert Israel_, Jan 05 2015

%o (PARI) a(n) = n - 1 + sum(j=0, n, j! ); \\ _Joerg Arndt_, Jan 06 2015

%Y Cf. A036781.

%K nonn

%O 0,2

%A _N. J. A. Sloane_