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

1,1

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

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 *)

Crossrefs

Cf. A007953, A104211.

Sequence in context: A175442 A020597 A140563 * A191052 A338173 A138889

Adjacent sequences: A154676 A154677 A154678 * A154680 A154681 A154682

Keyword

base,easy,nonn

Author

Giovanni Teofilatto, Jan 14 2009

Extensions

Extended by R. J. Mathar, Jan 15 2009

Status

approved