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 A228220 Number of second differences of arrays of length 5 of numbers in 0..n. 1
 31, 199, 625, 1429, 2731, 4651, 7309, 10825, 15319, 20911, 27721, 35869, 45475, 56659, 69541, 84241, 100879, 119575, 140449, 163621, 189211, 217339, 248125, 281689, 318151, 357631, 400249, 446125, 495379, 548131, 604501, 664609, 728575 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 20*n^3 + 9*n^2 + 1*n + 1. Conjectures from Colin Barker, Sep 10 2018: (Start) G.f.: x*(31 + 75*x + 15*x^2 - x^3) / (1 - x)^4. a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4) for n>4. (End) EXAMPLE Some solutions for n=4: .-2....1...-5....4....0....1....1....3...-2....4...-5...-8....4...-4....0....3 .-2...-2....6....0....2...-3....4....0....5....3....7....7...-6...-4....1...-7 .-2....5....0...-2...-5....7...-7...-2...-3...-6...-2...-2....3....4...-3....4 CROSSREFS Row 3 of A228218. Sequence in context: A139998 A142654 A137657 * A125341 A126499 A297758 Adjacent sequences: A228217 A228218 A228219 * A228221 A228222 A228223 KEYWORD nonn AUTHOR R. H. Hardin, Aug 16 2013 STATUS approved

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Last modified March 1 06:29 EST 2024. Contains 370430 sequences. (Running on oeis4.)