OFFSET
1,2
COMMENTS
Where nonnegative non-semiprime numbers are zero together with A100959 (i.e., 0, 1, 2, 3, 5, 7, 8, 11, 12, 13, 16, 17, 18, 19, 20, 23, 24, 27, 28, 29, 30, ...).
LINKS
Jinyuan Wang, Table of n, a(n) for n = 1..10000
EXAMPLE
1 is a term because nonnegative non-semiprime(1)+3 = 3 = nonnegative non-semiprime(1+3).
MAPLE
A100959 := proc(n) option remember; if n = 1 then 1; else for a from procname(n-1)+1 do if numtheory[bigomega](a) <> 2 then return a; end if; end do end if; end proc:
nnnspr := proc(n) if n = 1 then 0; else A100959(n-1) ; end if; end proc:
isA176650 := proc(n) nnnspr(n) + 3 = nnnspr(n+3) ; end proc:
for n from 1 to 1200 do if isA176650(n) then printf("%d, ", n) ; end if; end do:
# R. J. Mathar, Apr 26 2010
MATHEMATICA
Join[{1}, Flatten[With[{c=Select[Range[0, 300], PrimeOmega[#]!=2&]}, Position[ Partition [c, 4, 1], _?(#[[1]]+3==#[[4]]&), 1, Heads->False]]]+1] (* Harvey P. Dale, Oct 15 2022 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Juri-Stepan Gerasimov, Apr 22 2010
EXTENSIONS
Entries checked by R. J. Mathar, Apr 26 2010
STATUS
approved