A334142 Indices of twin primes.

2, 3, 4, 5, 6, 7, 8, 10, 11, 13, 14, 17, 18, 20, 21, 26, 27, 28, 29, 33, 34, 35, 36, 41, 42, 43, 44, 45, 46, 49, 50, 52, 53, 57, 58, 60, 61, 64, 65, 69, 70, 81, 82, 83, 84, 89, 90, 98, 99, 104, 105, 109, 110, 113, 114, 116, 117, 120, 121, 140, 141, 142, 143, 144, 145, 148, 149

Offset: 1

Author

Ilya Gutkovskiy, Apr 15 2020

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000
• Eric Weisstein's World of Mathematics, Twin Primes.

Crossrefs

Cf. A000720, A001097, A029707, A107770.

Programs

Maple

q:= n-> (p-> isprime(p-2) or isprime(p+2))(ithprime(n)):
select(q, [$1..150])[];  # Alois P. Heinz, Apr 15 2020

Mathematica

With[{p = PositionIndex[(#[[2]] - #[[1]] - 2) & /@ Partition[Prime[Range[150]], 2, 1]][0]}, Union[p, p + 1]] (* Amiram Eldar, Sep 06 2024 *)

Formula

a(n) = A000720(A001097(n)).

Set union of A029707 and A107770.