A176347 n-th semiprime minus sum of its prime factors.

0, 1, 3, 3, 5, 7, 11, 9, 15, 11, 19, 15, 23, 17, 23, 21, 35, 31, 39, 35, 27, 29, 47, 43, 35, 59, 39, 63, 41, 55, 71, 59, 45, 71, 51, 71, 87, 57, 95, 99, 59, 79, 83, 107, 65, 91, 69, 119, 111, 71, 119, 77, 103, 131, 81, 143, 115, 87, 119, 143, 159, 95, 131, 99, 167, 159, 101

Offset

1,3

Links

Table of n, a(n) for n=1..67.

Formula

a(n) = A001358(n) - A068318(n).

Maple

From R. J. Mathar, Apr 20 2010: (Start)
isA001358 := proc(n) numtheory[bigomega](n) = 2 ; end proc:
A001358 := proc(n) option remember ; if n = 1 then return 4 ; else for a from procname(n-1)+1 do if isA001358(a) then return a; end if; end do; end if; end proc:
A084126 := proc(n) min(op(numtheory[factorset](A001358(n)))) ; end proc:
A084127 := proc(n) max(op(numtheory[factorset](A001358(n)))) ; end proc:
A068318 := proc(n) A084126(n)+A084127(n) ; end proc:
A176347 := proc(n) A001358(n)-A068318(n) ; end proc: seq(A176347(n), n=1..80) ; (End)

Crossrefs

Sequence in context: A176513 A128424 A129758 * A161834 A141867 A163646

Adjacent sequences: A176344 A176345 A176346 * A176348 A176349 A176350

Keyword

nonn

Author

Juri-Stepan Gerasimov, Apr 15 2010

Extensions

Entries checked by R. J. Mathar, Apr 20 2010

Status

approved