A158195 Prime numbers such that sum of digits is even semiprime.

13, 19, 31, 37, 59, 73, 103, 109, 127, 149, 163, 167, 181, 211, 239, 257, 271, 293, 307, 347, 383, 419, 433, 491, 499, 509, 523, 541, 563, 613, 617, 631, 653, 743, 761, 769, 787, 811, 859, 877, 941, 967, 1009, 1021, 1049, 1063, 1117, 1153, 1171, 1193, 1201

Offset: 1

Author

Juri-Stepan Gerasimov, Mar 13 2009

Keywords

• nonn
• base
• easy
• less

Comments

Even semiprime = 2*prime.

Examples

			13(1+3=2*2), 19(1+9=2*5), 31(3+1=2*2), 37(3+7=2*5), 59(5+9=2*7).
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A000040, A100484.

Programs

Mathematica

Select[Prime[Range[200]],PrimeQ[Total[IntegerDigits[#]]/2]&] (* Peter J. C. Moses, Jun 05 2014 *)
Select[Prime[Range[200]],EvenQ[Total[IntegerDigits[#]]]&& PrimeOmega[ Total[ IntegerDigits[ #]]] ==2&] (* Harvey P. Dale, Sep 30 2016 *)

PARI

isok(n) = isprime(n) && (q = sumdigits(n)/2) && (type(q) == "t_INT") && isprime(q); \\ Michel Marcus, Jun 24 2014

Extensions

257 added by R. J. Mathar, Mar 15 2009