cp's OEIS Frontend

A084194 Even numbers n such that the sum of the digits is prime and the sum of the digits of n/2 is also prime.

%I A084194 #17 Sep 04 2019 15:55:44
%S A084194 14,32,50,58,76,94,98,104,122,140,148,166,184,188,212,230,238,256,274,
%T A084194 278,292,296,302,320,328,346,364,368,382,386,410,418,436,454,458,472,
%U A084194 476,490,494,500,508,526,544,548,562,566,580,584
%N A084194 Even numbers n such that the sum of the digits is prime and the sum of the digits of n/2 is also prime.
%C A084194 Sometimes n/2 is prime.
%H A084194 Robert Israel, <a href="/A084194/b084194.txt">Table of n, a(n) for n = 1..10000</a>
%e A084194 3+2=5 for n=32 and 1+6=7 for n/2=16;
%e A084194 5+8=13 for n=58 and 2+9=11 for n/2=29;
%e A084194 2+1+2=5 for n=212 and 1+0+6=7 for n/2=106;
%e A084194 2+5+6=13 for n=256 and 1+2+8=11 for n/2=128.
%p A084194 filter:= proc(n)
%p A084194   isprime(convert(convert(n,base,10),`+`)) and isprime(convert(convert(n/2,base,10),`+`))
%p A084194 end proc:
%p A084194 select(filter, [seq(i,i=2..1000,2)]); # _Robert Israel_, Sep 04 2019
%o A084194 (PARI) isok(n) = {if (n % 2, return (0)); dn = digits(n); dh = digits(n/2); isprime(sum(i=1, #dn, dn[i])) && isprime(sum(i=1, #dh, dh[i]));} \\ _Michel Marcus_, Aug 12 2013
%Y A084194 Cf. A084201.
%K A084194 base,nonn
%O A084194 1,1
%A A084194 _Patrick Capelle_, Jun 20 2003
%E A084194 More terms from _Michel Marcus_, Aug 12 2013