A091771 a(0) = 2; for n > 0, a(n) is the least prime of the form k*n*a(n-1) + 1.

2, 3, 7, 43, 173, 3461, 62299, 6977489, 55819913, 8038067473, 241142024191, 15915373596607, 2291813797911409, 476697269965573073, 20021285338554069067, 10811494082819197296181, 4670565443777893231950193

Offset

0,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..100

Mathematica

a[0] = 2; a[n_] := a[n] = Block[{k = 1}, While[ !PrimeQ[k*n*a[n - 1] + 1], k++ ]; k*n*a[n - 1] + 1]; Table[ a[n], {n, 0, 16}] (* Robert G. Wilson v, Feb 13 2004 *)
nxt[{n_, a_}]:=Module[{k=1}, While[!PrimeQ[k (n+1)a+1], k++]; {n+1, k(n+1)a+1}]; NestList[nxt, {0, 2}, 20][[;; , 2]] (* Harvey P. Dale, Mar 26 2023 *)

Crossrefs

Cf. A091879.

Sequence in context: A083369 A000946 A367020 * A339806 A072714 A051786

Adjacent sequences: A091768 A091769 A091770 * A091772 A091773 A091774

Keyword

nonn

Author

Amarnath Murthy, Feb 11 2004

Extensions

More terms from Ray Chandler, Robert G. Wilson v and Rick L. Shepherd, Feb 12 2004

Status

approved