A137988 Decimal expansion of the number whose Pierce expansion has the sequence of double factorial numbers (A000165) as coefficients.

3, 5, 2, 8, 0, 6, 4, 3, 8, 1, 0, 6, 6, 5, 0, 0, 3, 6, 4, 6, 2, 1, 2, 3, 6, 0, 5, 3, 1, 0, 7, 3, 0, 0, 8, 6, 3, 1, 1, 1, 4, 5, 9, 6, 9, 4, 4, 4, 9, 9, 0, 1, 7, 4, 0, 2, 7, 4, 9, 4, 6, 3, 1, 0, 7, 1, 8, 6, 4, 7, 0, 1, 5, 3, 3, 6, 5, 6, 5, 4, 4, 1, 4, 5, 6, 9, 0, 9, 1, 8, 9, 6, 0, 9, 4, 8, 3, 3, 9

Offset

0,1

Links

G. C. Greubel, Table of n, a(n) for n = 0..5000

Eric W. Weisstein, Pierce Expansion.

Eric W. Weisstein, Engel Expansion.

Maple

P:=proc(n) local a, i, j, k, w; a:=0; w:=1; for i from 0 by 1 to n do k:=i; j:=i-2; while j>0 do k:=k*j; j:=j-2; od; if (i=0 or i=1) then k:=1; fi; if i=2 then k:=2; fi; w:=w*k; a:=a+(-1)^i/w; print(evalf(a, 100)); od; end: P(100);

Mathematica

RealDigits[N[(Sum[(-1)^n*Product[1/((k + 1)!!), {k, 1, n}], {n, 1, 250}]), 100]][[1]] (* G. C. Greubel, Jan 01 2017 *)

Crossrefs

Cf. A000142, A137986, A137987, A137989.

Sequence in context: A208754 A180077 A095749 * A258367 A160092 A282348

Adjacent sequences: A137985 A137986 A137987 * A137989 A137990 A137991

Keyword

easy,nonn,cons

Author

Paolo P. Lava and Giorgio Balzarotti, Feb 26 2008

Status

approved