A065422 If n | a(n) then a(n+1) = a(n)/(highest power of n that divides a(n)), otherwise a(n+1) = n*a(n); a(0) = 1.

1, 1, 2, 6, 24, 120, 20, 140, 1120, 10080, 1008, 11088, 77, 1001, 14014, 210210, 3363360, 57177120, 1029188160, 19554575040, 977728752, 2217072, 100776, 2317848, 96577, 2414425, 62775050, 1694926350, 47457937800, 1376280196200

Offset: 0

Author

Naohiro Nomoto, Nov 23 2001

Keywords

• easy
• nonn
• nice
• look

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 0..1000
• Index entries for sequences related to Recamán's sequence

Crossrefs

See A008336 for another version. Cf. A005132.

Programs

Haskell

a065422 n = a065422_list !! n
a065422_list = 1 : 1 : f 2 1 where
   f n x = x' : f (n+1) x' where
       x' | x `mod` n == 0 = until ((> 0) . (`mod` n)) (`div` n) x
          | otherwise      = x * n
-- Reinhard Zumkeller, Oct 10 2011

Mathematica

nxt[{n_,a_}]:={n+1,If[Divisible[a,n],a/n^IntegerExponent[a,n],a*n]}; Join[ {1,1},Transpose[NestList[nxt,{3,2},30]][[2]]] (* Harvey P. Dale, Jan 08 2013 *)

Extensions

Definition and offset corrected by Reinhard Zumkeller, Oct 10 2011

Typo in Crossrefs fixed by Paul Tek, Aug 01 2015