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 1-3 of 3 results.

A107625 Every digit of prime and its index contains a loop (only digits 0,4,6,8,9 in prime and its index).

Original entry on oeis.org

409, 4409, 4999, 6869, 44699, 44909, 46499, 48409, 64849, 66889, 68449, 68909, 86969, 89689, 98869, 98899, 480499, 488689, 490499, 609809, 806609, 806999, 866969, 868669, 868849, 869489, 869849, 869899, 869909, 880949, 6440809, 6440999, 6488969, 6489449
Offset: 1

Views

Author

Zak Seidov, May 18 2005

Keywords

Comments

Corresponding indices in A107624. Cf. A001744 Every digit contains a loop.

Links

Crossrefs

Cf. A001744, A107624.

Programs

  • Mathematica
    Do[id=Union[IntegerDigits[p=Prime[n]], IntegerDigits[n]];If[Count[id, 1]+Count[id, 2]+Count[id, 3]+Count[id, 5]+Count[id, 7]==0, Print[p]], {n, 10000}]
Module[{c={0,4,6,8,9}},Select[Prime/@(Rest[FromDigits/@Tuples[c,6]]), SubsetQ[ c,IntegerDigits[#]]&]] (* Harvey P. Dale, Sep 03 2015 *)
  • PARI
    is_a001744(n) = #setintersect(vecsort(digits(n), , 8), [1, 2, 3, 5, 7])==0
my(i=1); forprime(p=1, 65e5, if(is_a001744(p) && is_a001744(i), print1(p, ", ")); i++) \\ Felix Fröhlich, Sep 09 2019

Extensions

More terms from Harvey P. Dale, Sep 03 2015

A107626 Numbers n such that every digit of both n and n^2 contains a loop (only digits 0,4,6,8,9 in n and n^2).

Original entry on oeis.org

8, 64, 80, 98, 640, 664, 800, 898, 980, 998, 6400, 6640, 6664, 8000, 8980, 8998, 9800, 9980, 9998, 64000, 66400, 66640, 66664, 80000, 89800, 89980, 89998, 98000, 98998, 99800, 99980, 99998, 640000, 664000, 664064, 666400, 666640, 666664, 684908, 800000, 806008
Offset: 1

Views

Author

Zak Seidov, May 18 2005

Keywords

Comments

Corresponding squares in A107627. Cf. A001744 Every digit contains a loop.

Crossrefs

Cf. A001744, A107624, A107625, A107627.

Programs

  • Mathematica
    Do[id=Union[IntegerDigits[n^2], IntegerDigits[n]];If[Count[id, 1]+Count[id, 2]+Count[id, 3]+Count[id, 5]+Count[id, 7]==0, Print[n]], {n, 10000}]
  • PARI
    is_a001744(n) = #setintersect(vecsort(digits(n), , 8), [1, 2, 3, 5, 7])==0
is(n) = is_a001744(n) && is_a001744(n^2) \\ Felix Fröhlich, Sep 09 2019

Extensions

More terms from Felix Fröhlich, Sep 09 2019

A107627 Numbers n such that every digit of n and sqrt(n) contains a loop (only digits 0,4,6,8,9 in n and sqrt(n)).

Original entry on oeis.org

64, 4096, 6400, 9604, 409600, 440896, 640000, 806404, 960400, 996004, 40960000, 44089600, 44408896, 64000000, 80640400, 80964004, 96040000, 99600400, 99960004
Offset: 1

Views

Author

Zak Seidov, May 18 2005

Keywords

Comments

Corresponding square roots in A107626. Cf. A001744 Every digit contains a loop.

Links

Crossrefs

Cf. A001744, A107624, A107625, A107626.

Programs

  • Mathematica
    Do[id=Union[IntegerDigits[n^2], IntegerDigits[n]];If[Count[id, 1]+Count[id, 2]+Count[id, 3]+Count[id, 5]+Count[id, 7]==0, Print[n^2]], {n, 10000}]
With[{c={0,4,6,8,9}},#^2&/@Select[FromDigits/@Tuples[c,4],SubsetQ[c,IntegerDigits[ #^2]]&]] (* Harvey P. Dale, Oct 01 2023 *)
Showing 1-3 of 3 results.

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

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