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

Author

N. J. A. Sloane, Feb 13 2017

Keywords

• nonn

Links

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

Crossrefs

Inspired by A007459 and A057459.

Programs

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

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 || 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(mJinyuan Wang, Nov 21 2020

Extensions

Corrected and extended by Robert Israel, Mar 17 2017

More terms from Jinyuan Wang, Nov 21 2020