A136355 Numbers of the form P = product of the first k odd primes where P+2 is composite.

1155, 255255, 4849845, 111546435, 152125131763605, 6541380665835015, 16294579238595022365, 58644190679703485491635, 3929160775540133527939545, 278970415063349480483707695, 20364840299624512075310661735

Offset

1,1

Comments

This sequence is different from A070826 and A118750

Links

Harvey P. Dale, Table of n, a(n) for n = 1..332

Example

a(1)=1155 because 1157 is not prime.

Mathematica

Contribution from Farideh Firoozbakht, Aug 12 2009: (Start)
v=Select[Range[20], !PrimeQ[Product[Prime[k+1], {k, #}]+2]&]; Table[Product[Prime
[k+1], {k, v[[t]]}], {t, Length[v]}] (End)
Select[FoldList[Times, Prime[Range[2, 21]]], CompositeQ[#+2]&] (* Harvey P. Dale, Jun 08 2022 *)

Crossrefs

Cf. A136349-A136354 A136356-A136358 A070826 A118750.

Sequence in context: A088012 A046406 A284846 * A321245 A157168 A062915

Adjacent sequences: A136352 A136353 A136354 * A136356 A136357 A136358

Keyword

easy,nonn

Author

Enoch Haga, Dec 25 2007

Extensions

Edited with more terms by Farideh Firoozbakht, Aug 12 2009

Status

approved