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 A247533 #8 Jul 23 2025 11:35:55 %S A247533 8,33,8,88,45,8,185,136,61,8,336,317,220,81,8,553,600,561,364,105,8, %T A247533 848,1033,1124,1007,604,153,8,1233,1616,2009,2164,1823,1018,217,8, %U A247533 1720,2409,3220,3997,4228,3455,1732,297,8,2321,3400,4901,6584,8051,8440,6495,2956 %N A247533 T(n,k)=Number of length n+3 0..k arrays with some disjoint pairs in every consecutive four terms having the same sum. %C A247533 Table starts %C A247533 .8..33...88...185....336....553....848....1233....1720....2321....3048....3913 %C A247533 .8..45..136...317....600...1033...1616....2409....3400....4661....6168....8005 %C A247533 .8..61..220...561...1124...2009...3220....4901....7016....9737...13000...17025 %C A247533 .8..81..364..1007...2164...3997...6584...10219...14852...20847...28108...37095 %C A247533 .8.105..604..1823...4228...8051..13668...21609...31924...45309...61740...82067 %C A247533 .8.153.1018..3455...8440..16683..29012...47061...70374..101211..139098..186709 %C A247533 .8.217.1732..6495..16932..34695..62108..103013..156308..227701..316236..428111 %C A247533 .8.297.2956.12105..34068..72269.133716..226309..349160..515043..723892..987667 %C A247533 .8.393.5050.22459..68688.150677.288996..498569..783568.1170169.1665908.2290065 %C A247533 .8.585.8638.43255.139040.318575.627654.1111891.1772920.2686215.3862654.5366083 %H A247533 R. H. Hardin, <a href="/A247533/b247533.txt">Table of n, a(n) for n = 1..9999</a> %F A247533 Empirical for column k: %F A247533 k=1: a(n) = a(n-1) %F A247533 k=2: a(n) = a(n-1) +4*a(n-4) -4*a(n-5) %F A247533 k=3: a(n) = 2*a(n-1) -a(n-3) +a(n-4) -a(n-5) -a(n-6) +a(n-7) %F A247533 k=4: [order 29] for n>30 %F A247533 k=5: [order 56] %F A247533 k=6: [order 82] for n>84 %F A247533 Empirical for row n: %F A247533 n=1: a(n) = 2*n^3 + 3*n^2 + 2*n + 1 %F A247533 n=2: a(n) = 2*a(n-1) +a(n-2) -4*a(n-3) +a(n-4) +2*a(n-5) -a(n-6); also a polynomial of degree 3 plus a linear quasipolynomial with period 2 %F A247533 n=3: [recurrence of order 12; also a polynomial of degree 3 plus a linear quasipolynomial with period 12] %F A247533 n=4: [recurrence of order 24; also a polynomial of degree 3 plus a linear quasipolynomial with period 420] %F A247533 n=5: [recurrence of order 48; also a polynomial of degree 3 plus a linear quasipolynomial with period 27720; note 2 12 420 27720 matches A060942] %F A247533 n=6: [recurrence of order 92] %e A247533 Some solutions for n=6 k=4 %e A247533 ..2....3....2....1....4....3....3....0....2....1....0....3....1....4....1....1 %e A247533 ..1....2....1....2....1....2....2....1....4....1....0....0....3....2....2....4 %e A247533 ..0....3....3....2....0....2....2....2....3....2....1....2....4....1....1....1 %e A247533 ..3....2....2....1....3....1....3....3....1....2....1....1....2....3....2....4 %e A247533 ..4....3....2....3....2....1....3....0....2....3....2....1....3....2....3....1 %e A247533 ..1....2....3....2....1....2....4....1....2....1....0....2....3....4....4....4 %e A247533 ..2....3....3....2....2....2....2....2....3....0....1....0....4....3....3....1 %e A247533 ..3....4....4....1....3....3....3....1....1....2....3....1....4....3....2....4 %e A247533 ..4....1....2....3....4....3....1....0....2....3....4....1....3....4....1....1 %Y A247533 Row 1 is A212133(n+1) %K A247533 nonn,tabl %O A247533 1,1 %A A247533 _R. H. Hardin_, Sep 18 2014