A175668 First differences of A175648.

4, 11, 1, 12, 1, 16, 7, 7, 17, 5, 4, 20, 4, 3, 1, 10, 12, 1, 13, 28, 18, 1, 3, 4, 4, 1, 1, 2, 32, 25, 13, 4, 4, 3, 1, 2, 4, 14, 4, 12, 23, 3, 16, 5, 9, 3, 9, 4, 4, 2, 34, 7, 15, 9, 3, 4, 4, 4, 4, 4, 10, 4, 14, 4, 5, 24, 17, 43, 7, 38, 14, 4, 9, 1, 4, 4, 10, 4, 28, 4, 14, 4, 14, 4, 4, 10, 4, 10

Offset: 1

Author

Juri-Stepan Gerasimov, Aug 05 2010

Keywords

• nonn

Comments

Distance between twin semiprime pairs.

Crossrefs

Cf. A053319, A175612, A175648.

Programs

Maple

A175648 := proc(n) option remember; if n = 1 then 6; else for a from procname(n-1)+1 do if numtheory[bigomega](a) = 2 and numtheory[bigomega](a+4) = 2 then return a; end if; end do: end if; end proc:
A175668 := proc(n) A175648(n+1)-A175648(n) ; end proc:
seq(A175668(n),n=1..100) ; # R. J. Mathar, Aug 07 2010

Extensions

Terms from a(33) on corrected by R. J. Mathar, Aug 07 2010