A131955 a(n) = sum of digits of (n!! + a(n-1)).

1, 3, 6, 5, 2, 5, 2, 17, 17, 23, 14, 23, 23, 23, 23, 23, 41, 41, 41, 41, 41, 50, 41, 59, 68, 59, 68, 59, 68, 86, 86, 104, 95, 95, 104, 86, 104, 86, 122, 95, 104, 113, 149, 95, 140, 95, 131, 122, 149, 140, 140, 113, 185, 149, 185, 149, 176, 194, 176, 185, 194, 194, 203

Offset

1,2

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Example

a(4) = Sum_digits(6+4!!) = Sum_digits(6+8) = Sum_digits(14) = 5.

Maple

A[1]:= 1:
for n from 2 to 100 do
  A[n]:= convert(convert(doublefactorial(n)+A[n-1], base, 10), `+`);
od:
seq(A[i], i=1..100); # Robert Israel, Oct 29 2020

Mathematica

s={1}; Do[AppendTo[s, DigitSum[n!!+s[[-1]]]], {n, 2, 63}]; s (* James C. McMahon, Mar 03 2025 *)

Crossrefs

Cf. A055263, A131954.

Sequence in context: A144179 A155540 A225451 * A249281 A316169 A346525

Adjacent sequences: A131952 A131953 A131954 * A131956 A131957 A131958

Keyword

easy,nonn,base,look

Author

Paolo P. Lava and Giorgio Balzarotti, Jul 31 2007

Extensions

Offset corrected by Robert Israel, Oct 29 2020

Status

approved