A138759 Indices for which A001203 (continued fraction for Pi) is prime.

1, 2, 9, 11, 14, 17, 18, 19, 20, 23, 27, 28, 31, 36, 37, 39, 40, 46, 48, 49, 50, 52, 59, 65, 70, 71, 72, 73, 75, 85, 86, 90, 93, 95, 97, 101, 102, 105, 106, 109, 110, 111, 118, 120, 122, 123, 124, 127, 128, 131, 132, 133, 140, 142, 145, 146, 151, 152, 153, 155, 159

Offset

1,2

Links

Table of n, a(n) for n=1..61.

Formula

k is in A138759 <=> A001203(k) is in A000040

Example

This sequence starts 1,2,9,11,... since the first, 2nd, 9th, 11th...
term of sequence A001203 = (3, 7, 15, 1, 292, 1, 1, 1, 2, ...) are primes.

Mathematica

Position[ContinuedFraction[Pi, 200], _?PrimeQ]//Flatten(* Harvey P. Dale, Aug 07 2019 *)

Prog

(PARI) default(realprecision, 1000); t=contfrac(Pi); for( k=1, #t, isprime(t[k]) & print1(k", "))

Crossrefs

Cf. A001203, A005042, A107892, A138758.

Sequence in context: A073634 A065554 A034042 * A345925 A098934 A237877

Adjacent sequences: A138756 A138757 A138758 * A138760 A138761 A138762

Keyword

nonn

Author

M. F. Hasler, Mar 31 2008

Status

approved