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 1-4 of 4 results.

A242824 Primes formed by the initial digits of the decimal expansion of 1/7, starting at the first nonzero digit in the expansion.

Original entry on oeis.org

1428571, 1428571428571428571428571
Offset: 1

Views

Author

Felix Fröhlich, May 23 2014

Keywords

Comments

Next term has 355 digits.
All terms are of the form 6x+1; a(4) has 823 digits; and there are no further terms up to and including 10000 digits. - Harvey P. Dale, Oct 03 2018

Links

Crossrefs

Cf. A020806, A241217.
Corresponding sequences for 1/k: A093676 (k=12), A242826 (k=13), A242827 (k=14), A242828 (k=17), A242833 (k=19).

Programs

  • Mathematica
    Select[Table[FromDigits[PadRight[{},6n+1,{1,4,2,8,5,7}]],{n,200}],PrimeQ](* Harvey P. Dale, Oct 03 2018 *)

A242833 Primes formed by the initial digits of the decimal expansion of 1/19, starting at the first nonzero digit in the expansion.

Original entry on oeis.org

5, 52631, 5263157894736842105263157, 52631578947368421052631578947368421052631578947368421052631
Offset: 1

Views

Author

Felix Fröhlich, May 23 2014

Keywords

Comments

a(5) has 95 digits and a(6) has 907 digits. - Michel Marcus, May 27 2014

Links

Crossrefs

Cf. A021023.
Corresponding sequences for 1/k: A242824 (k=7), A093676 (k=12), A242826 (k=13), A242827(k=14), A242828 (k=17).

Programs

  • PARI
    lista(nn) = {v = [5,2,6,3,1,5,7,8,9,4,7,3,6,8,4,2,1,0]; n = 0; for (i=0, nn, n = 10*n+ v[(i % 18)+1]; if (ispseudoprime(n), print1(n, ", ")););} \\ Michel Marcus, May 27 2014

A242827 Primes formed by the initial digits of the decimal expansion of 1/14, starting at the first nonzero digit in the expansion.

Original entry on oeis.org

7, 71, 71428571, 7142857142857, 7142857142857142857142857142857
Offset: 1

Views

Author

Felix Fröhlich, May 23 2014

Keywords

Comments

a(6) has 104 digits. - Michel Marcus, May 26 2014

Crossrefs

Cf. A021018.
Corresponding sequences for 1/k: A242824 (k=7), A093676 (k=12), A242826 (k=13), A242828 (k=17), A242833 (k=19).

Programs

  • PARI
    lista(nn) = {v = [7,1,4,2,8,5]; n = 0; for (i=0, nn, n = 10*n+ v[(i % 6)+1]; if (ispseudoprime(n), print1(n, ", ")););} \\ Michel Marcus, May 26 2014

A242828 Primes formed by the initial digits of the decimal expansion of 1/17, starting at the first nonzero digit in the expansion.

Original entry on oeis.org

5, 5882352941, 588235294117, 588235294117647058823529411764705882352941176470588235294117
Offset: 1

Views

Author

Felix Fröhlich, May 23 2014

Keywords

Comments

There is no other term with 126 or fewer digits.
No more terms < 10^20000. - Jon E. Schoenfield, Nov 02 2019

Crossrefs

Cf. A007450.
Corresponding sequences for 1/k: A242824 (k=7), A093676 (k=12), A242826 (k=13), A242827(k=14), A242833 (k=19).

Programs

  • Mathematica
    Select[Table[FromDigits[PadRight[{},n,{5,8,8,2,3,5,2,9,4,1,1,7,6,4,7,0}]],{n,60}],PrimeQ] (* Harvey P. Dale, Aug 08 2021 *)
  • PARI
    lista(nn) = {v = [5, 8, 8, 2, 3, 5, 2, 9, 4, 1, 1, 7, 6, 4, 7, 0]; n = 0; for (i=0, nn, n = 10*n+ v[(i % 16)+1]; if (ispseudoprime(n), print1(#Str(n), ", ")););} \\ Michel Marcus, May 27 2014
Showing 1-4 of 4 results.

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

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