A141451 a(1)=2. a(n) = the smallest integer > a(n-1) that is divisible by every exponent in the prime-factorization of a(n-1).

2, 3, 4, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 20, 22, 23, 24, 27, 30, 31, 32, 35, 36, 38, 39, 40, 42, 43, 44, 46, 47, 48, 52, 54, 57, 58, 59, 60, 62, 63, 64, 66, 67, 68, 70, 71, 72, 78, 79, 80, 84, 86, 87, 88, 90, 92, 94, 95, 96, 100, 102, 103, 104, 105, 106, 107, 108, 114, 115

Offset

1,1

Links

Table of n, a(n) for n=1..69.

Example

a(17) = 24. 24 has the prime factorization of 2^3 *3^1. So we want the smallest integer > 24 that is divisible by both 3 and 1, the exponents in the prime-factorization of 24. 27 is divisible by both 3 and 1, so a(18) = 27.

Maple

A141451 := proc(n) option remember ; local prev, ifs, a, gooda, e ; if n =1 then 2; else prev := procname(n-1) ; ifs := ifactors(prev)[2] ; for a from prev+1 do gooda := true; for e in ifs do if a mod op(2, e) <> 0 then gooda := false ; break; fi; od; if gooda then RETURN(a) ; fi; od: fi: end: for n from 1 to 120 do printf("%d, ", A141451(n)) ; od: # R. J. Mathar, Sep 12 2008

Crossrefs

Sequence in context: A137409 A037041 A048263 * A285211 A183217 A047303

Adjacent sequences: A141448 A141449 A141450 * A141452 A141453 A141454

Keyword

nonn

Author

Leroy Quet, Aug 07 2008

Extensions

Extended by R. J. Mathar, Sep 12 2008

Status

approved