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A202964 Number of arrays of 4 integers in -n..n with sum zero and adjacent elements differing in absolute value. 1
4, 28, 108, 268, 544, 972, 1576, 2392, 3456, 4792, 6436, 8424, 10780, 13540, 16740, 20404, 24568, 29268, 34528, 40384, 46872, 54016, 61852, 70416, 79732, 89836, 100764, 112540, 125200, 138780, 153304, 168808, 185328, 202888, 221524, 241272 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 2 of A202962.

LINKS

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

FORMULA

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

Empirical g.f.: 4*x*(1 + 4*x + 9*x^2 + 5*x^3 + 5*x^4) / ((1 - x)^4*(1 + x + x^2)). - Colin Barker, Jun 03 2018

EXAMPLE

Some solutions for n=5:

.-4....1...-1....0...-1....0....0....0....3...-2...-2...-5....0...-4....1...-5

..5...-4....2...-4....0...-3...-1...-2...-4...-1....5....4....3....1...-2....1

..2....1...-5....3....3....2....3....4...-2....5...-2....0....2....4....4....4

.-3....2....4....1...-2....1...-2...-2....3...-2...-1....1...-5...-1...-3....0

CROSSREFS

Cf. A202962.

Sequence in context: A077595 A201243 A092712 * A352322 A183469 A058227

Adjacent sequences:  A202961 A202962 A202963 * A202965 A202966 A202967

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 26 2011

STATUS

approved

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Last modified October 6 12:35 EDT 2022. Contains 357264 sequences. (Running on oeis4.)