A096477 Subscripts for "secondary twin-primes": numbers k such that prime(prime(k)+1) - prime(prime(k)) = A073124(k) = 2.

1, 2, 3, 4, 6, 7, 13, 14, 23, 24, 29, 30, 40, 59, 63, 65, 71, 74, 90, 103, 106, 110, 112, 117, 122, 128, 132, 187, 188, 193, 207, 248, 257, 258, 267, 271, 281, 285, 292, 296, 299, 300, 303, 304, 311, 317, 325, 340, 343, 344, 354, 356, 360, 368, 382, 389, 395, 402

Offset: 1

Author

Labos Elemer, Jun 23 2004

Keywords

• nonn

Examples

			24 is a term since prime(prime(24)+1) - prime(prime(24)) = prime(89+1) - prime(89) = 463 - 461 = 2.
		

Links

• Ivan Neretin, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A006450, A072677, A073124, A096478.

Programs

Mathematica

Flatten[Position[Table[Prime[Prime[n]+1]-Prime[Prime[n]], {n, 1, 1000}], 2]]

Formula

a(n) = primepi(A096478(n)). - Amiram Eldar, Aug 13 2024