A305318 Numbers k such that A071866(k)=3.

2, 3, 5, 6, 7, 10, 11, 12, 13, 17, 18, 20, 21, 24, 25, 26, 28, 29, 30, 33, 35, 36, 37, 41, 42, 43, 44, 45, 49, 50, 52, 53, 57, 58, 59, 60, 64, 65, 67, 69, 70, 73, 74, 78, 79, 81, 82, 83, 84, 87, 88, 89, 98, 99, 100, 104, 105, 109, 110, 111, 112, 113, 115, 116, 120, 121, 122, 125, 129, 130, 133

Offset: 1

Author

Robert Israel, May 29 2018

Keywords

• nonn

Comments

All terms are in A066940. The first member of A066940 not in this sequence is 61.

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000720, A066940, A071866, A275697. Contains A029707.

Programs

Maple

select(n -> nops(convert(ithprime(n+1)/ithprime(n),confrac))=3, [$1..1000]);

PARI

isok(n) = length(contfrac(prime(n+1)/prime(n))) == 3; \\ Michel Marcus, May 31 2018

Formula

a(n) = A000720(A275697(n+1)). - Robert Israel, May 31 2018