A176240 Primes of the form n-th semiprime-n.

3, 37, 37, 61, 61, 61, 71, 89, 89, 107, 113, 139, 139, 181, 199, 223, 227, 227, 269, 283, 293, 313, 313, 331, 347, 347, 349, 373, 373, 379, 401, 433, 433, 487, 487, 487, 503, 521, 521, 523, 557, 569, 569, 593, 647, 653, 653, 743, 757, 761, 773, 787, 797, 809

Offset

1,1

Comments

Generated by indices n = 1, 20, 21, 32,.. shown in A176241. [From R. J. Mathar, Apr 13 2010]

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

a(1)=3 because A001358(1)-1=4-1=3=prime.

Mathematica

Select[First[#]-Last[#]&/@Module[{sp=Select[Range[3000], PrimeOmega[#] == 2&], len}, len=Length[sp]; Thread[{sp, Range[len]}]], PrimeQ] (* Harvey P. Dale, Jan 28 2013 *)

Crossrefs

Sequence in context: A002563 A140448 A128061 * A116184 A037000 A042333

Adjacent sequences: A176237 A176238 A176239 * A176241 A176242 A176243

Keyword

nonn

Author

Juri-Stepan Gerasimov, Apr 12 2010

Extensions

More terms from R. J. Mathar, Apr 13 2010

Status

approved