OFFSET
1,1
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..500
EXAMPLE
131 is a term because the 131st semiprime is 415, the sum of the digits of 131 is 5, and 415/5 = 83, which is prime.
MAPLE
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:
A007953 := proc(n) add(d, d=convert(n, base, 10)) ; end proc:
isA176706 := proc(n) if isprime(n) then r := A001358(n)/A007953(n) ; if type(r, 'integer') then isprime(r) ; else false; end if; else false; end if; end proc:
for n from 1 to 2000 do p := ithprime(n) ; if isA176706(p) then printf("%d, ", p) ; end if; end do: # R. J. Mathar, Apr 24 2010
MATHEMATICA
Module[{semis=Select[Range[100000], PrimeOmega[#]==2&]}, Select[ Prime[ Range[ PrimePi[ Length[semis]]]], PrimeQ[semis[[#]]/ Total[ IntegerDigits[ #]]]&]] (* Harvey P. Dale, May 10 2014 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Juri-Stepan Gerasimov, Apr 24 2010
EXTENSIONS
Keyword:base added, sequence extended by R. J. Mathar, Apr 24 2010
STATUS
approved