OFFSET
1,2
COMMENTS
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
EXAMPLE
2 is a term because both semiprime(2)/3 = 6/3 = 2 and semiprime(2+1)/3 = 9/3 = 3 are prime.
MAPLE
isA176652 := proc(n) pfsn := convert(numtheory[factorset]( A001358(n) ), list) ; pfsn1 := convert(numtheory[factorset]( A001358(n+1) ), list) ; op(1, pfsn) = op(1, pfsn1) or op(1, pfsn) = op(-1, pfsn1) or op(-1, pfsn) = op(1, pfsn1) or op(-1, pfsn) = op(-1, pfsn1) ; end proc: for n from 1 to 1600 do if isA176652(n) then printf("%d, ", n) ; end if; end do: # R. J. Mathar, Apr 26 2010
MATHEMATICA
sppQ[{a_, b_}]:=Module[{af=FactorInteger[a][[All, 1]], bf=FactorInteger[b][[All, 1]]}, Length[Intersection[af, bf]]==1]; Position[Partition[ Select[ Range[7000], PrimeOmega[#]==2&], 2, 1], _?sppQ]//Flatten (* Harvey P. Dale, Oct 08 2017 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Juri-Stepan Gerasimov, Apr 22 2010
EXTENSIONS
Extended beyond 141 by R. J. Mathar, Apr 26 2010
Name clarified by Jon E. Schoenfield, Feb 06 2019
STATUS
approved