A282027 a(n+1) = smallest prime p > a(n) such that p-1 divides a(1)*a(2)*...*a(n); or if no such prime p exists, then a(n+1) = smallest prime > a(n).

2, 3, 7, 43, 47, 283, 659, 1319, 1699, 9227, 11887, 55399, 71359, 159707, 396719, 558643, 793439, 794039, 1117379, 1117943, 1143887, 2235887, 5554067, 6707747, 6863323, 13734803, 15667447, 16663963, 18214099, 20123239, 45196799, 46954223, 55937239, 93908447

Offset

1,1

Links

Jinyuan Wang, Table of n, a(n) for n = 1..200

Maple

A[1]:= 2: P:= 1:
for n from 2 to 30 do
  P:= A[n-1]*P;
  p0:= nextprime(A[n-1]);
  p:= p0;
  while p-1 <= P and P mod (p-1) <> 0 do
    p:= nextprime(p)
  od:
  if p-1 > P then A[n]:= p0
  else A[n]:= p
  fi;
od:
seq(A[i], i=1..30); # Robert Israel, Mar 17 2017

Prog

(PARI) lista(nn) = {my(d, k, m, t, v=List([2])); for(n=2, nn, k=1; m=oo; while((d=prod(i=1, t=k, v[i]))<m && k++<n, until(v[t]*d>m || t==n-1, t++); forsubset([t, k], w, if(ispseudoprime(d=prod(i=1, k, v[w[i]])+1) && d>v[n-1], m=min(m, d)))); listput(v, if(m<oo, m, nextprime(v[n-1]+1)))); v; } \\ Jinyuan Wang, Nov 21 2020

Crossrefs

Inspired by A007459 and A057459.

Sequence in context: A216826 A030087 A106864 * A255595 A085682 A267505

Adjacent sequences: A282024 A282025 A282026 * A282028 A282029 A282030

Keyword

nonn

Author

N. J. A. Sloane, Feb 13 2017

Extensions

Corrected and extended by Robert Israel, Mar 17 2017

More terms from Jinyuan Wang, Nov 21 2020

Status

approved