A048964 a(n) is smallest number k such that k! >= n-th primorial number (A002110(n)).
2, 3, 5, 6, 7, 8, 10, 11, 12, 14, 15, 16, 17, 19, 20, 21, 23, 24, 25, 27, 28, 29, 31, 32, 33, 34, 36, 37, 38, 40, 41, 42, 44, 45, 46, 47, 49, 50, 51, 53, 54, 55, 57, 58, 59, 60, 62, 63, 64, 66, 67, 68, 70, 71, 72, 73, 75, 76, 77, 79, 80, 81, 83, 84, 85, 86, 88, 89, 90, 92, 93
Offset: 1
Keywords
Examples
9! = 362880 < A002110(7) = 2*3*5*7*11*13*17 = 510510 <= 10! = 3628800, so a(7)=10. [edited by _Jon E. Schoenfield_, May 13 2018]
Links
- Giovanni Resta, Table of n, a(n) for n = 1..10000
Programs
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Mathematica
Primorial[n_] := Product[ Prime[i], {i, n}]; a[n_] := Block[{k = 1}, While[(k!) < Primorial[n], k++ ]; k]; Table[ a[n], {n, 71}] (* Robert G. Wilson v, Apr 09 2004 *) Module[{nn=100,pn,k=2},pn=FoldList[Times,Prime[Range[nn]]];Table[ While[ k!< pn[[n]],k++];k,{n,nn}]] (* Harvey P. Dale, Dec 12 2018 *) -
PARI
a(n) = {my(pr = prod(k=1, n, prime(k)), k = 0); while (k! < pr, k++); k;} \\ Michel Marcus, May 14 2018
Extensions
Edited by N. J. A. Sloane at the suggestion of Andrew S. Plewe, May 14 2007
Comments