A090186 a(n) is the least prime of the form prime(n)# * k + prime(n+1).

5, 11, 37, 431, 13873, 30047, 510529, 9699713, 446185769, 51757545871, 601681470427, 22262214404471, 2434002108217723, 13082761331670077, 1229779565176982873, 32589158477190044789, 1922760350154212639131

Offset

1,1

Comments

# denotes primorial; k >= 1.

Links

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

Example

a(4)=431 because prime(4)#*2+prime(5) = 431 is prime.

Mathematica

lp[{a_, b_}]:=Module[{k=1}, While[!PrimeQ[k*a+b], k++]; k*a+b]; With[{nn=20}, lp/@Thread[ {FoldList[Times, Prime[Range[nn]]], Prime[Range[2, nn+1]]}]] (* Harvey P. Dale, Dec 25 2018 *)

Crossrefs

Sequence in context: A152563 A077466 A074626 * A205719 A332475 A139515

Adjacent sequences: A090183 A090184 A090185 * A090187 A090188 A090189

Keyword

nonn

Author

Pierre CAMI, Jan 21 2004

Extensions

Edited by Don Reble, May 07 2006

Status

approved