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.

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A119224 Triangular numbers composed of digits {5,7,8}.

Original entry on oeis.org

55, 78, 5778, 7875, 8778, 75855, 887778, 7575778, 55888878, 57775875, 87787875, 88877778, 5587777755, 8888777778, 787575878775, 888887777778, 8857787887578, 88888877777778, 5777878558877778, 8888888777777778, 555875575755575778, 888888887777777778
Offset: 1

Views

Author

Giovanni Resta, May 10 2006

Keywords

Links

Crossrefs

Cf. A000217, A119225. See A119033 for a table of cross-references.

Formula

a(n) = A000217(A119225(n)). - Tyler Busby, Mar 26 2023

Extensions

a(21)-a(22) from Tyler Busby, Mar 26 2023

A119226 Triangular numbers composed of digits {5,7,9}.

Original entry on oeis.org

55, 595, 5995, 7779577597795, 9775779559755, 57575799959759975575, 77777755779995957575, 7577959575775997959995995979795
Offset: 1

Views

Author

Giovanni Resta, May 10 2006

Keywords

Comments

a(9) > 10^40. - Tyler Busby, Mar 29 2023

Links

Crossrefs

Cf. A000217, A119227. See A119033 for a table of cross-references.

Formula

a(n) = A000217(A119227(n)). - Michel Marcus, Mar 27 2023

A119228 Triangular numbers composed of digits {5,8,9}.

Original entry on oeis.org

55, 595, 5995, 555985, 85989999559555, 5558888585898885, 898989555999995895, 559585958899855598985, 988889885885555858595, 85889898559958558998859955, 5595888555988988898588558558585, 8589985889588895598998885898885995, 88988559899558559855895555589855985
Offset: 1

Views

Author

Giovanni Resta, May 10 2006

Keywords

Comments

a(14) > 10^40. - Tyler Busby, Mar 26 2023

Links

Crossrefs

Cf. A000217, A058470, A119229. See A119033 for a table of cross-references.

Formula

a(n) = A000217(A119229(n)). - Tyler Busby, Mar 26 2023

Extensions

a(12)-a(13) from Tyler Busby, Mar 26 2023

A119232 Triangular numbers composed of digits {6,7,9}.

Original entry on oeis.org

6, 66, 666, 677766969666676, 66799696699976679697696799766996696
Offset: 1

Views

Author

Giovanni Resta, May 10 2006

Keywords

Comments

a(6) > 10^40. - Tyler Busby, Mar 29 2023

Links

Crossrefs

Cf. A000217, A053973, A119233. See A119033 for a table of cross-references.

Formula

a(n) = A000217(A119233(n)). - Michel Marcus, Mar 27 2023

Extensions

a(5) from Max Alekseyev, Mar 10 2009

A119234 Triangular numbers composed of digits {6,8,9}.

Original entry on oeis.org

6, 66, 666, 68898988866, 88698868996686886, 696999969866686966889999889666
Offset: 1

Views

Author

Giovanni Resta, May 10 2006

Keywords

Comments

a(7) > 10^37. - Max Alekseyev, Apr 30 2010
a(7) > 10^40. - Tyler Busby, Mar 29 2023

Links

Crossrefs

Cf. A000217, A053975, A119235. See A119033 for a table of cross-references.

Formula

a(n) = A000217(A119235(n)). - Michel Marcus, Mar 27 2023

A218390 Triangular numbers composed of digits {0,2,4}.

Original entry on oeis.org

40002040, 2442040424202042204020040, 24202244424402424242222220, 200020020000400442044244444400204400200
Offset: 1

Views

Author

Max Alekseyev, Oct 27 2012

Keywords

Comments

a(5) > 10^40.

Links

Crossrefs

Cf. A000217, A218389. See A119033 for a table of cross-references.

Formula

a(n) = A000217(A218389(n)).

A218397 Triangular numbers composed of digits {0,2,7}.

Original entry on oeis.org

70007020020, 27272070272700, 20720272227227700077007700020, 22200020770272007007202277772702722200
Offset: 1

Views

Author

Max Alekseyev, Oct 28 2012

Keywords

Comments

a(5) > 10^40.

Links

Crossrefs

Cf. A000217, A218398. See A119033 for a table of cross-references.

Formula

a(n) = A000217(A218398(n)).

A218399 Triangular numbers composed of digits {0,4,7}.

Original entry on oeis.org

40470, 4744740, 4770740040, 44747000047470770470774700707404004740
Offset: 1

Views

Author

Max Alekseyev, Oct 28 2012

Keywords

Comments

a(5) > 10^40.

Links

Crossrefs

Cf. A000217, A218400. See A119033 for a table of cross-references.

Formula

a(n) = A000217(A218400(n)).

A218401 Triangular numbers composed of digits {0,7,9}.

Original entry on oeis.org

990, 90779090007770790, 79909779970709079970099779979097777700
Offset: 1

Views

Author

Max Alekseyev, Oct 28 2012

Keywords

Comments

a(4) > 10^40.

Links

Crossrefs

Cf. A000217, A218402. See A119033 for a table of cross-references.

Formula

a(n) = A000217(A218402(n)).

A118706 Triangular numbers whose digits in base 12 are contained in {1,5,7,11}.

Original entry on oeis.org

1, 91, 1891, 3403, 403651, 4388203, 4468555, 41710411, 201553003, 213283531, 410970115, 428264011, 633021571, 642342403, 703181251, 4913725411, 28007409475, 41103462403, 90151709131, 90294438403, 337594212451, 443352832075, 1452321801451, 1483280069635, 4435473488491
Offset: 1

Views

Author

Walter Kehowski, May 24 2006

Keywords

Comments

In base 12 all primes greater than 3 end in a 1, 5, 7, or E, where X is 10 and E is eleven. In base 12 the sequence is 1, 77, 1117, 1E77, 175717, 1577577, 15E5E77, 11E75E77, 575EE577, 5E517E77, E5771E17, EE511E77, 157EE7E17, 15E151E17, 1775E1717, E5171E117, 551775E717, 7E71571E17, 1557E75EE77, 155EE511E17, 55517751117, 71E11E71E77. Note that all elements after the first either end in 17 or 77. In base 12 the n such that t=n(n+1)/2 end in the digits 1 or X, but not respectively.

Examples

			a(4) = 3403 = 1E77 in base 12.

Crossrefs

Cf. A000217, A118711, A119033, A119034.

Programs

  • Maple
    L:=[]: pd:={1,5,7,11}: for w to 1 do for n from 1 to 10^6 do t:=n*(n+1)/2; lod:=convert(t,base,12); sod:=convert(lod,set); if sod subset pd then L:=[op(L),[n,t]] fi; od od; L;
  • Mathematica
    Select[Accumulate[Range[822000]],SubsetQ[{1,5,7,11},IntegerDigits[ #,12]]&] (* Harvey P. Dale, Oct 18 2019 *)

Formula

a(n) = t if t is the n-th triangular number such that S subset {1,5,7,11}, where S is the set of digits of t in base 12.
a(n) = A000217(A118711(n)). - Amiram Eldar, Aug 02 2024

Extensions

a(22)-a(25) from Amiram Eldar, Aug 02 2024
Previous Showing 101-110 of 112 results. Next

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