A256043 Order of all-2s configuration on the 2n X 2n sandpile grid graph.

1, 1, 3, 29, 901, 89893, 5758715, 22687425, 97725875584681, 27985118605791989, 858944872773025112243, 3844747107219467355553841461, 38892662235512583998213091903, 262356551554779841189525814045832317, 1860824505363724621907762698492068045341627

Offset

0,3

Links

Table of n, a(n) for n=0..14.

Laura Florescu, Daniela Morar, David Perkinson, Nicholas Salter, Tianyuan Xu, Sandpiles and Dominos, Illustration of recurrent identity element for the sandpile grid graph [Figure 1 from Sandpiles and Dominos paper] [Le Borgne et al., 2002, show a very similar figure - see Fig. 7.]

Laura Florescu, Daniela Morar, David Perkinson, Nicholas Salter, and Tianyuan Xu, Sandpiles and Dominos, Electronic Journal of Combinatorics, Volume 22(1), 2015. Also arXiv:1406.0100, May 31 2014. [Mentions this sequence together with a different sequence (A065072) with the same initial terms]

Le Borgne, Yvan, and Dominique Rossin, On the identity of the sandpile group, Discrete mathematics 256.3 (2002): 775-790.

David Perkinson, Lecture 15: Sandpiles, PCMI 2008 Undergraduate Summer School. Gives a(7).

Crossrefs

Cf. A065072, A256047, A391052.

Bisection of A256046, which is the main diagonal of A256045.

Sequence in context: A243435 A064570 A117264 * A065072 A088389 A270883

Adjacent sequences: A256040 A256041 A256042 * A256044 A256045 A256046

Keyword

nonn

Author

N. J. A. Sloane, Mar 14 2015

Extensions

a(7) added by Scott R. Shannon, Apr 23 2019

a(0) and a(8) onwards from Andrei Zabolotskii, Dec 01 2025

Status

approved