0,34

In other words, a(n) is the number of ways to write n as the sum of two anagrams.

Leading zeros are ignored.

Rémy Sigrist, Table of n, a(n) for n = 0..20000

Rémy Sigrist, PARI program for A331218

Rémy Sigrist, Scatterplot of (x, y) such that 0 <= x, y <= 10^3 and x and y are decimal anagrams (a(n) corresponds to the number of pixels (x, y) such that x+y = n)

For n = 44:

- we have the following ways to write 44 as a sum of two anagrams:

u v

-- --

13 31

22 22

31 13

- hence a(44) = 3.

(PARI) See Links section.

Cf. A330827 (ternary analog), A331216 (binary analog).

Sequence in context: A247477 A072927 A307194 * A120086 A215030 A175816

Adjacent sequences: A331215 A331216 A331217 * A331219 A331220 A331221

nonn,base

Rémy Sigrist, Jan 12 2020

approved