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 A159376 Number of n X n arrays of squares of integers with every (n-1) X (n-1) subblock summing to 9. 2
 40, 5670, 1311488, 139966840, 8517111552, 256972682203, 4498018289528, 52749621622223, 457173827246752, 3130129802580412, 17742633295703592, 86151806412861614, 367633855676693776, 1406125033775057961, 4895690201780964016, 15709764651757551137, 46932167419266807288 (list; graph; refs; listen; history; text; internal format)
 OFFSET 3,1 LINKS R. H. Hardin, Table of n, a(n) for n = 3..27 Index entries for linear recurrences with constant coefficients, signature (19, -171, 969, -3876, 11628, -27132, 50388, -75582, 92378, -92378, 75582, -50388, 27132, -11628, 3876, -969, 171, -19, 1). FORMULA a(n) = (213086953*n^18 - 7234157232*n^17 + 109387042419*n^16 - 944291714616*n^15 + 4732047974274*n^14 - 8876879623584*n^13 - 60234921458282*n^12 + 630926806905936*n^11 - 3155566369823715*n^10 + 10733292326883024*n^9 - 26950021111932873*n^8 + 51435177242228136*n^7 - 75424820511654584*n^6 + 85302351200676672*n^5 - 74679591278805264*n^4 + 50936307964412544*n^3 - 26904530479120128*n^2 + 10180065773445120*n - 2048904435916800)/65840947200. - Robert Israel, Dec 19 2023 MAPLE G:= proc(s, m) option remember; local t; if s = 9 then t:= m else t:= 0 fi; # 9, 0* if s >= 8 then t:= t + expand(m!/(2*(s-8)!*(m-(s-8)-2)!)) fi; # 4, 4, 1*, 0&* if s >= 4 then t:= t + expand(m!/(s-4)!/(m-(s-4)-1)!) fi; # 4, 1*, 0* t + expand(m!/(s!*(m-s)!)); # 1*, 0* end proc: t:= 0: for a in [0, 1, 4, 9] do for c in [0, 1, 4, 9] do for b from 0 to 9 - max(a, c) do for d from 0 to 9 - a - b do e:= 9 - a - b - d; f:= 9 - b - c - e; if f < 0 then next fi; for g in [0, 1, 4, 9] do h:= 9 - d - e - g; if h < 0 then next fi; i:= 9 - e - f - h; if not member(i, [0, 1, 4, 9]) then next fi; t:= t + G(b, n-2) * G(d, n-2) * G(f, n-2) * G(h, n-2) * G(e, (n-2)^2) od od od od od: Q:= normal(t): seq(Q, n=3..30); # Robert Israel, Dec 19 2023 CROSSREFS Sequence in context: A123810 A275655 A146198 * A364507 A196706 A196855 Adjacent sequences: A159373 A159374 A159375 * A159377 A159378 A159379 KEYWORD nonn,easy AUTHOR R. H. Hardin, Apr 11 2009 STATUS approved

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Last modified September 17 08:27 EDT 2024. Contains 375986 sequences. (Running on oeis4.)