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.

14, 32, 50, 58, 76, 94, 98, 104, 122, 140, 148, 166, 184, 188, 212, 230, 238, 256, 274, 278, 292, 296, 302, 320, 328, 346, 364, 368, 382, 386, 410, 418, 436, 454, 458, 472, 476, 490, 494, 500, 508, 526, 544, 548, 562, 566, 580, 584

Offset: 1

Author

Patrick Capelle, Jun 20 2003

Keywords

• base
• nonn

Comments

Sometimes n/2 is prime.

Examples

			3+2=5 for n=32 and 1+6=7 for n/2=16;
5+8=13 for n=58 and 2+9=11 for n/2=29;
2+1+2=5 for n=212 and 1+0+6=7 for n/2=106;
2+5+6=13 for n=256 and 1+2+8=11 for n/2=128.
		

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A084201.

Programs

Maple

filter:= proc(n)
  isprime(convert(convert(n,base,10),`+`)) and isprime(convert(convert(n/2,base,10),`+`))
end proc:
select(filter, [seq(i,i=2..1000,2)]); # Robert Israel, Sep 04 2019

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

Extensions

More terms from Michel Marcus, Aug 12 2013