A282974 Numbers k such that A011546(k-1) is a prime.

1, 2, 6, 12, 1902, 3971, 5827, 16208, 47577

Offset

1,2

Comments

Round(k)=floor(k) or floor(k)+1, so if round(k)=floor(k) and floor(k) is a prime number, then round(k) is also prime. Thus 47577 = A060421(6) and 613373 = A060421(8) are also terms.

The corresponding primes are in A282973.

a(10) > 2^16. - Lucas A. Brown, Apr 05 2021

Links

Table of n, a(n) for n=1..9.

Lucas A. Brown, A282974.py

Eric Weisstein's World of Mathematics, Pi-Prime

Mathematica

Do[If[PrimeQ[Round[Pi*10^(n-1)]], Print[n], {n, 17511}]

Prog

(PARI) default(realprecision, 10^5); x=Pi;
is(k) = ispseudoprime(round(x*10^k--)); \\ Jinyuan Wang, Mar 27 2020

Crossrefs

Cf. A000796, A005042, A011546, A060421, A282973.

Sequence in context: A126293 A007668 A089415 * A181063 A161324 A226603

Adjacent sequences: A282971 A282972 A282973 * A282975 A282976 A282977

Keyword

nonn,base,more

Author

XU Pingya, Feb 25 2017

Extensions

a(8) and a(9) from Lucas A. Brown, Apr 05 2021

Definition corrected by Lucas A. Brown, Apr 05 2021

Status

approved