A120762 a(1) = 2. a(n) = a(n-1)*(largest prime occurring earlier in the sequence) + 1.

2, 5, 26, 131, 17162, 2248223, 5054506657730, 11363658121561713791, 25548037553031840864343394, 57437685631589904363556698288863, 129132725903709949557948530897082440450

Offset

1,1

Links

Harvey P. Dale, Table of n, a(n) for n = 1..29

Example

Among the first 3 terms of the sequence, 5 is the largest prime. So a(4) = a(3)*5 +1 = 26*5 + 1 = 131.

Mathematica

nxt[{lp_, a_}]:=Module[{c=a lp+1}, {If[PrimeQ[c]&&c>lp, c, lp], c}]; NestList[nxt, {2, 2}, 12][[;; , 2]] (* Harvey P. Dale, Apr 14 2023 *)

Prog

(PARI) {m=11; print1(a=2, ", "); v=[a]; for(n=2, m, b=a; v=vecsort(v); j=#v; a=0; while(a<1, k=v[j]; if(isprime(k), print1(a=b*k+1, ", "); v=concat(v, a), j--)))} - (Klaus Brockhaus, Aug 17 2006)

Crossrefs

Cf. A120763.

Sequence in context: A090878 A214951 A333004 * A226170 A371614 A334639

Adjacent sequences: A120759 A120760 A120761 * A120763 A120764 A120765

Keyword

nonn

Author

Leroy Quet, Jul 03 2006

Extensions

More terms from Klaus Brockhaus, Aug 17 2006

Status

approved