0,3

Table of n, a(n) for n=0..104.

a(n) =A056562(n)+A056563(n) =number of primes (with multiplicity) in {m, m+1, 2m-1, 2m+3}

a(2)=3 because 2nd triangular number is 3 and all three of 3-0=3, 3-1=2 and 6-3=3 are prime [n=2 is the only case where there is multiplicity].

Cf. A000217, A001227, A056562, A0565643

Sequence in context: A249355 A064654 A162229 * A082844 A279124 A101406

Adjacent sequences: A056561 A056562 A056563 * A056565 A056566 A056567

nonn

Henry Bottomley, Jun 27 2000

approved