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 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. 3

%I

%S 14,32,50,58,76,94,98,104,122,140,148,166,184,188,212,230,238,256,274,

%T 278,292,296,302,320,328,346,364,368,382,386,410,418,436,454,458,472,

%U 476,490,494,500,508,526,544,548,562,566,580,584

%N 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 Sometimes n/2 is prime.

%H Robert Israel, <a href="/A084194/b084194.txt">Table of n, a(n) for n = 1..10000</a>

%e 3+2=5 for n=32 and 1+6=7 for n/2=16;

%e 5+8=13 for n=58 and 2+9=11 for n/2=29;

%e 2+1+2=5 for n=212 and 1+0+6=7 for n/2=106;

%e 2+5+6=13 for n=256 and 1+2+8=11 for n/2=128.

%p filter:= proc(n)

%p isprime(convert(convert(n,base,10),`+`)) and isprime(convert(convert(n/2,base,10),`+`))

%p end proc:

%p select(filter, [seq(i,i=2..1000,2)]); # _Robert Israel_, Sep 04 2019

%o (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 Cf. A084201.

%K base,nonn

%O 1,1

%A _Patrick Capelle_, Jun 20 2003

%E More terms from _Michel Marcus_, Aug 12 2013

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Last modified January 25 10:12 EST 2022. Contains 350565 sequences. (Running on oeis4.)