A048880 Primes of form pq+2 where p and q are consecutive primes.

17, 37, 79, 223, 439, 4759, 22501, 32401, 53359, 57601, 60493, 72901, 77839, 95479, 99223, 159199, 164011, 176401, 194479, 239119, 324901, 378223, 416023, 497011, 680623, 756853, 804511, 1115113, 1664101, 1742401, 2223079

Offset

1,1

Comments

All terms > 17 are congruent to 1 mod 6. - Zak Seidov, Dec 03 2010

Links

T. D. Noe, Table of n, a(n) for n=1..1000

Formula

a(n) = 6*A342564(n-1) + 1 for n >= 2. - Hugo Pfoertner, Jun 24 2021

Example

487*491+2=239119.

Maple

with (numtheory): for n from 1 to 1000 do if (tau(ithprime(n)*ithprime(n+1)+2)=2) then print(ithprime(n), ithprime(n+1), ithprime(n)*ithprime(n+1)+2); fi; od;

Mathematica

Reap[Do[If[PrimeQ[p=Prime[k]*Prime[k+1]+2], Sow[p]], {k, 1, 430}]][[2, 1]] (* Zak Seidov Dec 03 2010 *)

Crossrefs

Cf. A051507, A123921, A342564.

Sequence in context: A200865 A319245 A093930 * A075892 A155143 A261529

Adjacent sequences: A048877 A048878 A048879 * A048881 A048882 A048883

Keyword

easy,nonn

Author

Herman H. Rosenfeld (herm3(AT)pacbell.net)

Extensions

Corrected and extended by Joe DeMaio (jdemaio(AT)kennesaw.edu).

Status

approved