A200044 Starting with a(1)=1, a(n) = n*a(n-1) if n>= a(n-1), otherwise a(n) = a(n-1)-n.

1, 2, 6, 2, 10, 4, 28, 20, 11, 1, 11, 132, 119, 105, 90, 74, 57, 39, 20, 400, 379, 357, 334, 310, 285, 259, 232, 204, 175, 145, 114, 82, 49, 15, 525, 489, 452, 414, 375, 335, 294, 252, 209, 165, 120, 74, 27, 1296, 1247, 1197, 1146, 1094

Offset

1,2

Links

Ivan Neretin, Table of n, a(n) for n = 1..9119

Example

Start with 1, then as 2 is bigger than 1, 1 * 2 = 2. As n=3 is bigger than 2, 2 * 3 = 6. As n=4 is smaller than 6, 6 - 4 = 2, then 2 * 5 = 10, then 10 - 6 = 4, then 4 * 7 = 28, etc

Maple

A200044 := proc(n)
    option remember;
    if n = 1 then
        1;
    elif n >= procname(n-1) then
        n*procname(n-1) ;
    else
        procname(n-1)-n ;
    end if;
end proc:
seq(A200044(n), n=1..80) ; # R. J. Mathar, Jan 28 2012

Mathematica

a = {1}; Do[AppendTo[a, If[a[[-1]] <= n, a[[-1]]*n, a[[-1]] - n]], {n, 2, 52}]; a (* Ivan Neretin, May 20 2015 *)
nxt[{n_, a_}]:={n+1, If[n+1>=a, a(n+1), a-n-1]}; NestList[nxt, {1, 1}, 60][[All, 2]] (* Harvey P. Dale, Oct 20 2016 *)

Crossrefs

Sequence in context: A267859 A002172 A126289 * A154382 A136762 A136697

Adjacent sequences: A200041 A200042 A200043 * A200045 A200046 A200047

Keyword

nonn,easy

Author

Rodolfo Kurchan, Nov 12 2011

Status

approved