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 1-9 of 9 results.

A086080 Number of 9's in decimal expansion of triangular number n(n+1)/2.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0
Offset: 0

Views

Author

Jason Earls, Jul 08 2003

Keywords

Links

Crossrefs

Cf. A000217.
Cf. 0's A086071, 1's A086072, 2's A086073, 3's A086074, 4's A086075, 5's A086076, 6's A086077, 7's A086078, 8's A086079.

Programs

  • Mathematica
    DigitCount[Accumulate[Range[0, 100]], 10, 9] (* Paolo Xausa, May 05 2024 *)
  • PARI
    A086080(n) = length(select(d -> (9==d),digits(binomial(n+1,2)))); \\ Antti Karttunen, Sep 27 2018; corrected by Georg Fischer Apr 28 2021

Extensions

Zero at the beginning inserted by Antti Karttunen, Sep 27 2018
Zero at the beginning removed by Georg Fischer, Apr 28 2021

A086071 Number of 0's in decimal expansion of triangular number n(n+1)/2.

Original entry on oeis.org

1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 2, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 1, 2, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 2, 1, 1, 1, 0, 1, 0, 1, 0, 0, 0, 0, 2, 1, 0, 0, 0, 0, 1, 0, 0, 0, 1, 2, 0, 0, 0, 1
Offset: 0

Views

Author

Jason Earls, Jul 08 2003

Keywords

Examples

			tri(4)=10, so a(4)=1 and tri(24)=300, so a(24)=2.

Links

Crossrefs

Cf. 1's A086072, 2's A086073, 3's A086074, 4's A086075, 5's A086076, 6's A086077, 7's A086078, 8's A086079, 9's A086080.
Cf. A000217.

Programs

  • Mathematica
    DigitCount[Accumulate[Range[0, 100]], 10, 0] (* Paolo Xausa, May 05 2024 *)

A086075 Number of 4's in decimal expansion of triangular number n(n+1)/2.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 0, 0, 1, 0, 0, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1
Offset: 0

Views

Author

Jason Earls, Jul 08 2003

Keywords

Links

Crossrefs

Cf. 0's A086071, 1's A086072, 2's A086073, 3's A086074, 5's A086076, 6's A086077, 7's A086078, 8's A086079, 9's A086080.

Programs

  • Mathematica
    DigitCount[Accumulate[Range[0, 100]], 10, 4] (* Paolo Xausa, May 05 2024 *)

A086078 Number of 7's in decimal expansion of triangular number n(n+1)/2.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 2, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0
Offset: 0

Views

Author

Jason Earls, Jul 08 2003

Keywords

Links

Crossrefs

Cf. 0's A086071, 1's A086072, 2's A086073, 3's A086074, 4's A086075, 5's A086076, 6's A086077, 8's A086079, 9's A086080.
Cf. A000217.

Programs

  • Mathematica
    DigitCount[Accumulate[Range[0, 100]], 10, 7] (* Paolo Xausa, May 05 2024 *)

A086079 Number of 8's in decimal expansion of triangular number n(n+1)/2.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 2, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0
Offset: 0

Views

Author

Jason Earls, Jul 08 2003

Keywords

Links

Crossrefs

Cf. 0's A086071, 1's A086072, 2's A086073, 3's A086074, 4's A086075, 5's A086076, 6's A086077, 7's A086078, 9's A086080.
Cf. A000217.

Programs

  • Mathematica
    DigitCount[Accumulate[Range[0, 100]], 10, 8] (* Paolo Xausa, May 05 2024 *)

A086072 Number of 1's in decimal expansion of triangular number n(n+1)/2.

Original entry on oeis.org

0, 1, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 2, 1, 1, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 2, 2, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 3, 1, 1, 2, 1, 1, 0, 1, 2, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 0, 2, 0, 0, 0
Offset: 0

Views

Author

Jason Earls, Jul 08 2003

Keywords

Examples

			tri(6)=21, so a(6)=1 and tri(1541)=1188111, so a(1541)=5.

Crossrefs

Cf. 0's A086071, 2's A086073, 3's A086074, 4's A086075, 5's A086076, 6's A086077, 7's A086078, 8's A086079, 9's A086080.

Programs

  • Mathematica
    Table[DigitCount[(n(n+1))/2,10,1],{n,0,110}] (* Harvey P. Dale, Apr 24 2011 *)
DigitCount[#,10,1]&/@Accumulate[Range[0,110]] (* Harvey P. Dale, Jun 25 2014 *)

A086073 Number of 2's in decimal expansion of triangular number n(n+1)/2.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 2, 2, 1, 1, 1, 1, 2, 1, 1, 1, 2, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0
Offset: 0

Views

Author

Jason Earls, Jul 08 2003

Keywords

Examples

			tri(49)=1225, so a(49)=2 and tri(651)=212226, so a(651)=4.

Crossrefs

Cf. 0's A086071, 1's A086072, 3's A086074, 4's A086075, 5's A086076, 6's A086077, 7's A086078, 8's A086079, 9's A086080.

Programs

  • Mathematica
    DigitCount[#,10,2]&/@Accumulate[Range[0,120]] (* Harvey P. Dale, Jan 02 2016 *)

A086074 Number of 3's in decimal expansion of triangular number n(n+1)/2.

Original entry on oeis.org

0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 1, 1, 1, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 2, 1, 1, 1, 2, 2, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 0
Offset: 0

Views

Author

Jason Earls, Jul 08 2003

Keywords

Crossrefs

Cf. 0's A086071, 1's A086072, 2's A086073, 4's A086075, 5's A086076, 6's A086077, 7's A086078, 8's A086079, 9's A086080.

Programs

  • Mathematica
    DigitCount[#,10,3]&/@Accumulate[Range[0,110]] (* Harvey P. Dale, Aug 01 2017 *)

A086076 Number of 5's in decimal expansion of triangular number n(n+1)/2.

Original entry on oeis.org

0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 2, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 1, 1, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 1, 2, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 0, 0, 0, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 1
Offset: 0

Views

Author

Jason Earls, Jul 08 2003

Keywords

Crossrefs

Cf. 0's A086071, 1's A086072, 2's A086073, 3's A086074, 4's A086075, 6's A086077, 7's A086078, 8's A086079, 9's A086080.

Programs

  • Mathematica
    DigitCount[#,10,5]&/@Accumulate[Range[0,110]] (* Harvey P. Dale, Sep 24 2016 *)
Showing 1-9 of 9 results.

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