A228219 Number of second differences of arrays of length 4 of numbers in 0..n.

15, 49, 103, 177, 271, 385, 519, 673, 847, 1041, 1255, 1489, 1743, 2017, 2311, 2625, 2959, 3313, 3687, 4081, 4495, 4929, 5383, 5857, 6351, 6865, 7399, 7953, 8527, 9121, 9735, 10369, 11023, 11697, 12391, 13105, 13839, 14593, 15367, 16161, 16975, 17809

Offset

1,1

Comments

Row 2 of A228218.

Links

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

Formula

Empirical: a(n) = 10*n^2 + 4*n + 1 = A272039(n).

Conjectures from Colin Barker, Mar 16 2018: (Start)

G.f.: x*(15 + 4*x + x^2) / (1 - x)^3.

a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n>3.

(End)

Example

Some solutions for n=4:
..1....1....1....5....6....1....2...-5....8....4...-5....8....1....5...-7....0
..4....2...-3....1...-6....1....1...-1...-7....1....0...-4....5...-7....6....6

Crossrefs

Cf. A228218, A272039.

Sequence in context: A154060 A168305 A208155 * A272039 A241577 A199899

Adjacent sequences: A228216 A228217 A228218 * A228220 A228221 A228222

Keyword

nonn

Author

R. H. Hardin, Aug 16 2013

Status

approved