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.
%I A202661 #7 Jun 02 2025 07:26:32 %S A202661 11,91,587,2833,10205,37505,136999,501903,1838983,6737379,24684959, %T A202661 90444993,331378703,1214138477,4448501629,16298925281,59717838711, %U A202661 218801046307,801668385089,2937244370963,10761811926301,39430358807041 %N A202661 Number of -5..5 arrays of n elements with first through fourth differences also in -5..5. %C A202661 Column 5 of A202664 %H A202661 R. H. Hardin, <a href="/A202661/b202661.txt">Table of n, a(n) for n = 1..210</a> %e A202661 Some solutions for n=6 %e A202661 .-2...-2...-3....1...-1...-1....1....0....5...-2....0....3....2....2...-3....5 %e A202661 .-3....3...-4....2....1...-3....3....3....0...-2....3...-2....2...-2....0....4 %e A202661 .-2....3...-4....4....0...-1....3....1....0...-2....2...-2....0...-3...-1....1 %e A202661 ..1....1...-3....5....0....2....2...-2....0...-3....0...-1...-1...-3...-3...-1 %e A202661 ..1...-3....0....3....2....2....0...-4....0...-3....0....1....1...-4...-3....0 %e A202661 .-4...-4....5....1....3....0...-5...-3....2....1....0....3....3...-3...-1....3 %K A202661 nonn %O A202661 1,1 %A A202661 _R. H. Hardin_ Dec 22 2011