|
%I #2 Mar 31 2012 14:40:00
%S 34,16,37,97,79,301,151,361,371,391,322,922,142,172,772,382,313,133,
%T 943,763,373,383,793,124,334,934,754,364,325,745,395,106,706,316,916,
%U 346,166,376,196,907,727,337,937,757,377,328,358,958,388,709,929,769,799
%N Primes that are not Chen primes written backwards.
%p # Check if number is Chen prime ischenprime:=proc(n); if (isprime(n) = 'true') then if (isprime(n+2) = 'true' or numtheory[bigomega](n+2) = 2) then return 'true' else return 'false' fi fi end: #Reverse digits obrni_stev:=proc(n) local i, tren, tren1, st, ans; ans:=[ ]: tren:=n: tren1:=0: for i while (tren>0) do st:=round(10*frac(tren/10)): ans:=[op(ans), st]: tren:=trunc(tren/10): od: for i from 0 to nops(ans)-1 do tren1:= tren1 + op(nops(ans)-i, ans)*10^(i): od: return tren1 end: ts_inv_nonchen_pra:= proc(n) local i, trens, ans; trens:= [ ]; ans:=[ ]; for i from 1 to n do if (ischenprime( i ) = 'false') then ans:=[op(ans),obrni_stev(i)] fi: od: return ans end: ts_inv_nonchen_pra(2000);
%Y Cf. A004087, A102540, A109611.
%K nonn,base,less
%O 1,1
%A _Jani Melik_, May 05 2006
|
