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.

A068149 Triangular numbers in which neighboring digits differ at most by 1. Allowed neighbors of 9 are 0, 8 and 9.

Table of values

n a(n)
1 0
2 1
3 3
4 6
5 10
6 21
7 45
8 55
9 66
10 78
11 210
12 666
13 990
14 2211
15 3321
16 5565
17 6555
18 8778
19 10011
20 90100
21 112101
22 222111
23 232221
24 443211
25 887778
26 5433456
27 5456556
28 5656566
29 5676765
30 22221111
31 22321221
32 34565455
33 88877778
34 211099878
35 212210901

List of values

[0, 1, 3, 6, 10, 21, 45, 55, 66, 78, 210, 666, 990, 2211, 3321, 5565, 6555, 8778, 10011, 90100, 112101, 222111, 232221, 443211, 887778, 5433456, 5456556, 5656566, 5676765, 22221111, 22321221, 34565455, 88877778, 211099878, 212210901]

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

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