OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
EXAMPLE
97 is the 25th prime number but not a Chen prime since 99 = 3*3*11, therefore 25 is in the sequence.
MAPLE
ts_inde_nonchen:= proc(n) local i, ans, inde; ans:=[ ]: inde := 0; for i from 1 to n do if ( isprime(i) = 'true') then inde:=inde+1: if (isprime(i+2) = 'false' and numtheory[bigomega](i+2) <> 2) then ans:=[ op(ans), inde ] fi fi od: return ans end: ts_inde_nonchen(2000);
MATHEMATICA
Select[Range[180], Sum[FactorInteger[Prime[ # ]+2][[i, 2]], {i, 1, Length[ FactorInteger[Prime[ # ] + 2]]}] > 2 &]
PROG
(PARI) isok(k) = (bigomega(prime(k)+2) > 2); \\ Michel Marcus, Oct 19 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Jani Melik, May 05 2006
EXTENSIONS
Edited by Stefan Steinerberger, Jul 19 2007
STATUS
approved