cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-2 of 2 results.

A060421 Numbers k such that the first k digits of the decimal expansion of Pi form a prime.

Original entry on oeis.org

1, 2, 6, 38, 16208, 47577, 78073, 613373
Offset: 1

Views

Author

Michel ten Voorde, Apr 05 2001

Keywords

Comments

The Brown link states that in 2001 Ed T. Prothro reported discovering that 16208 gives a probable prime and that Prothro verified that all values for 500 through 16207 digits of Pi are composites. - Rick L. Shepherd, Sep 10 2002
The corresponding primes are in A005042. - Alexander R. Povolotsky, Dec 17 2007

Examples

			3 is prime, so a(1) = 1; 31 is prime, so a(2) = 2; 314159 is prime, so a(3) = 6; ...

Links

Crossrefs

Cf. A000796 (Pi), A005042, A007523, A047658.
Primes in other constants: A064118 (e), A065815 (gamma), A064119 (phi), A118328 (Catalan's constant), A115377 (sqrt(2)), A119344 (sqrt(3)), A228226 (log 2), A228240 (log 10), A119334 (zeta(3)), A122422 (Soldner's constant), A118420 (Glaisher-Kinkelin constant), A174974 (Golomb-Dickman constant), A118327 (Khinchin's constant).
In other bases: A065987 (binary), A065989 (ternary), A065991 (quaternary), A065990 (quinary), A065993 (senary).

Programs

  • Mathematica
    Do[If[PrimeQ[FromDigits[RealDigits[N[Pi, n + 10], 10, n][[1]]]], Print[n]], {n, 1, 9016} ]

Extensions

a(6) = 47577 from Eric W. Weisstein, Apr 01 2006
a(7) = 78073 from Eric W. Weisstein, Jul 13 2006
a(8) = 613373 from Adrian Bondrescu, May 29 2016

A189658 Positions of 0 in A064990; complement of A189659.

Original entry on oeis.org

1, 2, 4, 5, 9, 10, 11, 13, 14, 18, 21, 24, 25, 26, 28, 29, 31, 32, 36, 37, 38, 40, 41, 45, 48, 51, 52, 53, 57, 60, 61, 62, 66, 69, 70, 71, 73, 74, 76, 77, 81, 82, 83, 85, 86, 90, 91, 92, 94, 95, 99, 102, 105, 106, 107, 109, 110, 112, 113, 117, 118, 119, 121, 122, 126, 129, 132, 133, 134, 138, 141, 142, 143, 147, 150, 151, 152, 154, 155, 157, 158, 162, 165, 168, 169, 170
Offset: 1

Views

Author

Clark Kimberling, Apr 25 2011

Keywords

Comments

See A065990.

Crossrefs

Cf. A064990, A189659, A189660.

Programs

Showing 1-2 of 2 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement.