A245723 a(n) = position of the first occurrence of n in A245714.

1, 3, 7, 19, 109, 509, 241, 317, 181, 1471, 2503, 2491, 7151, 11779, 3361, 2927, 1733, 5881, 15893, 16943, 11639, 31897, 25939, 12011, 17123, 6283, 10369, 63949, 8471, 125261, 64579, 117541, 21859, 58879, 44711, 216829, 64081, 67159, 73273, 181931, 139709

Offset

1,2

Comments

Least m > 0 such that m+n! is the smallest prime of form m+k!. - Jens Kruse Andersen, Jul 30 2014

Links

Vaclav Kotesovec and Jens Kruse Andersen, Table of n, a(n) for n = 1..200 (first 92 terms from Vaclav Kotesovec)

Example

a(2) = 3 since 3+2! is the smallest prime of the form 3+k!, and 3 is the least such number. While 1+2! is also prime, there is a smaller prime 1+1! in that case so a(2) is not 1. - Jens Kruse Andersen, Jul 30 2014

Mathematica

nmax=2000; Table[nn=1; k=0; While[k!=n && nn<nmax, k=1; While[Not[PrimeQ[nn+k!]] && k<=nn, k++]; If[k>nn, k=0]; nn++]; If[nn==nmax, 0, nn-1], {n, 1, 10}]

Prog

(PARI)
a(n)=for(k=1, n, if(ispseudoprime(n+k!), return(k)))
b(n)=for(k=1, 10^6, if(a(k)==n, return(k)))
n=1; while(n<150, print1(b(n), ", "); n++) \\ Derek Orr, Jul 30 2014

Crossrefs

Cf. A245714.

Sequence in context: A146037 A172514 A128024 * A118128 A113875 A111974

Adjacent sequences: A245720 A245721 A245722 * A245724 A245725 A245726

Keyword

nonn

Author

Vaclav Kotesovec, Jul 30 2014

Status

approved