login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A245874 Number of length 5+2 0..n arrays with some pair in every consecutive three terms totalling exactly n. 1
42, 553, 1764, 4753, 9726, 18505, 31176, 50401, 76050, 111721, 156972, 216433, 289254, 381193, 490896, 625345, 782586, 970921, 1187700, 1442641, 1732302, 2067913, 2445144, 2876833, 3357666, 3902185, 4503996, 5179441, 5920950, 6746761 (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) = 2*a(n-1) + 2*a(n-2) - 6*a(n-3) + 6*a(n-5) - 2*a(n-6)  -2*a(n-7) + a(n-8).

Conjectures from Colin Barker, Nov 04 2018: (Start)

G.f.: x*(42 + 469*x + 574*x^2 + 371*x^3 + 10*x^4 - 121*x^5 - 2*x^6 + x^7) / ((1 - x)^5*(1 + x)^3).

a(n) = 1 + 12*n + 26*n^2 + 39*n^3 + 7*n^4 for n even.

a(n) = -9 - 18*n + 23*n^2 + 39*n^3 + 7*n^4 for n odd.

(End)

EXAMPLE

Some solutions for n=10:

..9....4...10....8....2....8....7....8....7....7....6....9....3....2....5....0

..0....6....0....2....6....4....1....4....0....4....4....7....7....1....5....4

.10....6...10....3....4....6....9....2...10....6....6....3....3....9....5...10

..0....4....7....7....6....1....3....8....3....8....4....7....4...10....6....0

..5....0....3....8....4....9....7...10....7....2...10....5....7....1....4....4

.10...10....9....2....6....1....7....0...10....8....0....5....3....9....6....6

..0....5....1....6....7....3....3....9....0....8....8....2....2....2....8....8

CROSSREFS

Row 5 of A245869.

Sequence in context: A196671 A248448 A248449 * A293096 A279888 A104901

Adjacent sequences:  A245871 A245872 A245873 * A245875 A245876 A245877

KEYWORD

nonn

AUTHOR

R. H. Hardin, Aug 04 2014

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified July 29 07:28 EDT 2021. Contains 346340 sequences. (Running on oeis4.)