A140365 a(n) = sum of primes in {6*n-5, 6*n-1}.

5, 18, 30, 42, 29, 31, 78, 90, 53, 59, 61, 138, 73, 162, 89, 0, 198, 210, 222, 0, 0, 258, 137, 139, 149, 151, 157, 330, 173, 179, 181, 191, 390, 199, 0, 211, 0, 450, 462, 239, 241, 251, 257, 263, 269, 271, 558, 283, 293, 0, 0, 618, 630, 0, 0, 331, 337, 347, 702

Offset

1,1

Links

Table of n, a(n) for n=1..59.

Formula

a(n) = (6n-5)*isprime(6n-5) + (6n-1)*isprime(6n-1), where isprime = A010051. - M. F. Hasler, Jun 15 2008

Example

6*11 - 5 = 61 is prime, but 6*11 - 1 = 65 is not prime, so a(11) = 61.

Maple

a:= n-> add(i, i=select(isprime, [6*n-5, 6*n-1])):
seq(a(n), n=1..59);  # Alois P. Heinz, May 18 2021

Prog

(PARI) a(n)=(6*n-5)*isprime(6*n-5)+(6*n-1)*isprime(6*n-1) \\ M. F. Hasler, Jun 15 2008
(Python)
from sympy import isprime
def a(n): return sum(k*isprime(k) for k in {6*n-5, 6*n-1})
print([a(n) for n in range(1, 60)]) # Michael S. Branicky, May 18 2021

Crossrefs

Cf. A002476, A007528.

Sequence in context: A155450 A322409 A287894 * A063294 A063141 A154609

Adjacent sequences: A140362 A140363 A140364 * A140366 A140367 A140368

Keyword

nonn

Author

Juri-Stepan Gerasimov, Jun 10 2008

Extensions

Edited by M. F. Hasler, Jun 15 2008

a(52) corrected and a(58) deleted by Michael S. Branicky, May 18 2021

Status

approved