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A175668 First differences of A175648. 1
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Distance between twin semiprime pairs.

LINKS

Table of n, a(n) for n=1..88.

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

CROSSREFS

Cf. A053319, A175612, A175648.

Sequence in context: A230024 A132150 A091389 * A113249 A087171 A282026

Adjacent sequences:  A175665 A175666 A175667 * A175669 A175670 A175671

KEYWORD

nonn

AUTHOR

Juri-Stepan Gerasimov, Aug 05 2010

EXTENSIONS

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

STATUS

approved

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Last modified May 16 21:28 EDT 2021. Contains 343951 sequences. (Running on oeis4.)