1,1

Except for the first term, all the others are multiples of 3.

Vincenzo Librandi, Table of n, a(n) for n = 1..5000

Eric Weisstein's World of Mathematics, Cousin Primes

The digit sum of the cousin prime pairs 223 and 227 is: 2+2+3+2+2+7 = 18.

cptot[n_]:=Total[Join[IntegerDigits[n], IntegerDigits[n+4]]]; cptot/@Select[ Prime[Range[500]], PrimeQ[#+4]&] (* Harvey P. Dale, Apr 27 2014 *)

Cf. A023200, A166173, A167607

Sequence in context: A231471 A063661 A154533 * A063596 A284518 A309660

Adjacent sequences: A167605 A167606 A167607 * A167609 A167610 A167611

base,nonn

Parthasarathy Nambi, Nov 07 2009

approved