A140890 a(n) = sum of primes in {10*n-9, 10*n-7, 10*n-3, 10*n-1}.

10, 60, 52, 68, 131, 112, 128, 223, 172, 97, 420, 113, 127, 407, 149, 308, 330, 352, 181, 780, 0, 211, 679, 472, 241, 508, 532, 548, 564, 293, 307, 941, 0, 668, 696, 712, 367, 752, 772, 397, 810, 419, 421, 1303, 892, 457, 1391, 479, 487, 990, 1012, 0, 1044, 0

Offset: 1

Author

Juri-Stepan Gerasimov, Jul 06 2008

Keywords

• nonn

Examples

			a(1) = 3 + 7 = 10.
a(11) = 101 + 103 + 107 + 109 = 420.
a(21) = 0 (there are no primes in {201, 203, 207, 209}).
		

Crossrefs

Cf. A030430, A030431, A030432, A030433.

Programs

Mathematica

f[n_]:=Plus@@Select[10n-{9,7,3,1},PrimeQ]; Table[f[n],{n,60}] (* Ray Chandler, Feb 20 2009 *)

PARI

a(n)=(10*n-9)*isprime(10*n-9) + (10*n-7)*isprime(10*n-7) + (10*n-3)*isprime(10*n-3) + (10*n-1)*isprime(10*n-1) \\ M. F. Hasler, Jun 15 2008

Formula

a(n) = (10n-9) isprime (10n-9) + (10n-7) isprime (10n-7) + (10n-3) isprime (10n-3) + (10n-1) isprime (10n-1), where isprime = A010051. - M. F. Hasler, Jun 15 2008

Extensions

Corrected and extended by Ray Chandler, Feb 20 2009