A214632 a(1) = 17, a(n) is smallest prime of the form k*a(n - 1) + 1.

17, 103, 619, 2477, 34679, 416149, 7490683, 29962733, 419478263, 5872695683, 82217739563, 986612874757, 27625160493197, 994505777755093, 5967034666530559, 71604415998366709, 6444397439853003811, 180443128315884106709, 9743928929057741762287

Offset

1,1

Comments

Sequence does not begin with 2 (17 = 8*2 + 1; all primes are k*2+1) because 3 = 1*2 + 1 or 5 = 2*2 + 1 are smaller; and they would lead to A061092, or A059411. Also: 7 belongs to A061092; 11 to A059411 and 13 is a(1) in A214523.

Links

Harvey P. Dale, Table of n, a(n) for n = 1..300

Example

a(2) = 103 = 6*17 + 1.

Mathematica

t = {17}; Do[k = 1; While[p = k*t[[-1]] + 1; ! PrimeQ[p], k++]; AppendTo[t, p], {20}]; t (* T. D. Noe, Jul 24 2012 *)
nxt[n_]:=Module[{k=1}, While[!PrimeQ[k*n+1], k++]; k*n+1]; NestList[nxt, 17, 20] (* Harvey P. Dale, Apr 18 2014 *)

Crossrefs

Cf. A061092, A059411, A214523.

Sequence in context: A078625 A254757 A142266 * A160219 A242316 A329386

Adjacent sequences: A214629 A214630 A214631 * A214633 A214634 A214635

Keyword

nonn

Author

Robin Garcia, Jul 23 2012

Status

approved