A154679 Primes p such that the sum of digits of p+2 is a composite number.

2, 7, 11, 13, 17, 29, 31, 37, 43, 53, 61, 67, 71, 73, 79, 89, 97, 101, 103, 107, 127, 139, 151, 157, 163, 167, 179, 181, 193, 211, 223, 229, 233, 241, 251, 257, 269, 271, 277, 283, 293, 307, 313, 331, 337, 347, 349, 359, 367, 373, 379, 383, 397, 409, 421, 431

Offset: 1

Author

Giovanni Teofilatto, Jan 14 2009

Keywords

• base
• easy
• nonn

Comments

Primes p such that p+2 is in A104211. [R. J. Mathar, Jan 15 2009]

Links

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

Crossrefs

Cf. A007953, A104211.

Programs

Maple

filter:= proc(n) local s;
if not isprime(n) then return false fi;
s:= convert(convert(n+2,base,10),`+`);
s >= 4 and not isprime(s)
end proc:
select(filter, [$2..1000]); # Robert Israel, Mar 13 2019

Mathematica

Select[Prime[Range[100]],CompositeQ[Total[IntegerDigits[#+2]]]&] (* Harvey P. Dale, Apr 28 2022 *)

Extensions

Extended by R. J. Mathar, Jan 15 2009