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A202077 Number of arrays of 5 integers in -n..n with sum zero and the sum of every adjacent pair being odd. 1
2, 26, 78, 264, 504, 1128, 1786, 3262, 4660, 7540, 10092, 15066, 19278, 27174, 33644, 45428, 54846, 71622, 84770, 107780, 125532, 156156, 179478, 219234, 249184, 299728, 337456, 400582, 447330, 524970, 582072, 676296, 745178, 858194, 940374 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 3 of A202076.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = a(n-1) + 4*a(n-2) - 4*a(n-3) - 6*a(n-4) + 6*a(n-5) + 4*a(n-6) - 4*a(n-7) - a(n-8) + a(n-9).

Conjectures from Colin Barker, May 26 2018: (Start)

G.f.: 2*x*(1 + 12*x + 22*x^2 + 45*x^3 + 22*x^4 + 12*x^5 + x^6) / ((1 - x)^5*(1 + x)^4).

a(n) = (230*n^4 + 552*n^3 + 424*n^2 + 96*n) / 384 for n even.

a(n) = (230*n^4 + 368*n^3 + 148*n^2 + 16*n + 6) / 384 for n odd.

(End)

EXAMPLE

Some solutions for n=3:

  -2  0  0 -2  0  2  0  0  2  2 -2  2  2  2 -2  2

  -1 -1 -3  1 -1 -1 -1  3  1 -3  3  1 -3 -3  1 -3

   0  2  2  0  0  0  2 -2 -2 -2  2  0  0  2 -2  0

   1 -3  1 -1 -1 -1  1 -1 -1  3 -3 -3 -1 -1  3  3

   2  2  0  2  2  0 -2  0  0  0  0  0  2  0  0 -2

CROSSREFS

Cf. A202076.

Sequence in context: A152997 A229573 A067204 * A280212 A120551 A120547

Adjacent sequences:  A202074 A202075 A202076 * A202078 A202079 A202080

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 10 2011

STATUS

approved

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Last modified September 17 06:00 EDT 2019. Contains 327119 sequences. (Running on oeis4.)