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.

A119109 Triangular numbers composed of digits {1,2,9}.

Original entry on oeis.org

1, 21, 91, 2211, 222111, 22221111, 229119121, 291212911, 2222211111, 222222111111, 299992122991, 1122921211191, 22222221111111, 2222222211111111, 21212929921912191, 222222222111111111, 22222222221111111111, 2222222222211111111111, 191929912211129991991191
Offset: 1

Views

Author

Giovanni Resta, May 10 2006

Keywords

Links

Crossrefs

Cf. A000217, A053889, A119110. See A119033 for a table of cross-references.

Formula

a(n) = A000217(A119110(n)). - Tyler Busby, Mar 31 2023

Extensions

a(17)-a(19) from Tyler Busby, Mar 22 2023

A053888 Numbers k such that k^2 contains only digits {1,2,9}.

Original entry on oeis.org

1, 3, 11, 173, 3161, 34827, 43923, 44623, 54123, 1108661, 9603239, 14832161, 9960980373, 1513668461761, 99961098929489127, 459556524411439511, 145303131149776986249167839
Offset: 1

Views

Author

Patrick De Geest, Mar 15 2000

Keywords

Links

Crossrefs

Cf. A053889.

Extensions

More terms from C. Ronaldo (aga_new_ac(AT)hotmail.com), Jan 04 2005
One more term from Jon E. Schoenfield, Sep 03 2006
Two more terms from Mishima's webpage added by Max Alekseyev, Jun 17 2011
a(17) from Zhao Hui Du, Feb 29 2024
Showing 1-2 of 2 results.

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

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