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 A212928 #11 Jul 04 2025 19:21:35 %S A212928 462,724082352,68264066143602,4051316109991426752, %T A212928 207406617181155352354002,10046278068363977051128904352, %U A212928 475997448692406224810330915906802 %N A212928 Number of nX6 0..5 arrays with no column j greater than column j-1 in all rows. %C A212928 Column 6 of A212930. %H A212928 R. H. Hardin, <a href="/A212928/b212928.txt">Table of n, a(n) for n = 1..210</a> %F A212928 Empirical: a(n) = 84893*a(n-1) -2276359483*a(n-2) +25831810460691*a(n-3) -141600299635779300*a(n-4) +393253940006658385200*a(n-5) -543914412861962657592000*a(n-6) +355178573601133735540800000*a(n-7) -106850312683474117501440000000*a(n-8) +12875773990520518094592000000000*a(n-9) -350101309136762266214400000000000*a(n-10) +337332030823872921600000000000000*a(n-11). %F A212928 Empirical: a(n) = 46656^n -5*19440^n -1 -3*540^n -6*1800^n +6*8100^n -3375^n +400^n +4*4320^n +2*225^n +2*36^n. - _R. J. Mathar_, Jun 27 2012 %e A212928 Some solutions for n=3 %e A212928 ..4..3..4..2..3..5....4..1..5..5..5..1....5..0..3..5..0..2....2..4..5..3..5..4 %e A212928 ..3..2..0..3..5..5....0..3..3..3..4..5....0..5..2..3..5..5....0..3..4..3..3..0 %e A212928 ..3..5..1..3..2..1....1..0..0..2..0..3....1..4..1..0..2..4....5..0..0..2..2..3 %K A212928 nonn %O A212928 1,1 %A A212928 _R. H. Hardin_ May 31 2012