A072488 a(1) = 1, a(n) = a(n-1) times largest divisor of n <= n^(1/2).

1, 1, 1, 2, 2, 4, 4, 8, 24, 48, 48, 144, 144, 288, 864, 3456, 3456, 10368, 10368, 41472, 124416, 248832, 248832, 995328, 4976640, 9953280, 29859840, 119439360, 119439360, 597196800, 597196800, 2388787200, 7166361600, 14332723200, 71663616000

Offset

1,4

Links

Table of n, a(n) for n=1..35.

Mathematica

nxt[{n_, a_}]:=Module[{divs=Reverse[Divisors[n+1]]}, {n+1, a*SelectFirst[ divs, #<=Sqrt[n+1]&]}]; Transpose[NestList[nxt, {1, 1}, 40]][[2]] (* The program uses the SelectFirst function from Mathematica version 10 *) (* Harvey P. Dale, Jun 12 2015 *)

Prog

(PARI) A033676(n) = {local(d); if(n<2, 1, d=divisors(n); d[(length(d)+1)\2])} A072488(n) = if(n<2, 1, A033676(n)*A072488(n-1)) a=1; print(a); for(n=2, 100, a=a*A033676(n); print(a))

Crossrefs

Cf. A072489.

Sequence in context: A118406 A355811 A357214 * A285437 A286089 A287489

Adjacent sequences: A072485 A072486 A072487 * A072489 A072490 A072491

Keyword

nonn

Author

Amarnath Murthy, Jul 13 2002

Extensions

PARI program from Michael B. Porter, Jan 30 2010

Status

approved