A201087 Number of -7..7 arrays of n elements with first and second differences also in -7..7

15, 169, 1483, 13405, 121371, 1100401, 9975741, 90429601, 819732439, 7430807385, 67359774511, 610611788991, 5535153486929, 50175781165245, 454839969853999, 4123092739091885, 37375549329244061, 338806758784131711

Offset

1,1

Comments

Column 7 of A201088

Links

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

Formula

Empirical: a(n) = 9*a(n-1) -5*a(n-2) +38*a(n-3) +114*a(n-4) -2*a(n-5) +95*a(n-6) -19*a(n-7) -939*a(n-8) -482*a(n-9) +502*a(n-10) -1068*a(n-11) -59*a(n-12) +4668*a(n-13) +2468*a(n-14) -3545*a(n-15) -170*a(n-16) +1736*a(n-17) -6616*a(n-18) -4688*a(n-19) +6542*a(n-20) +2785*a(n-21) -5266*a(n-22) +595*a(n-23) +5562*a(n-24) +1303*a(n-25) -2419*a(n-26) -1843*a(n-27) +136*a(n-28) +845*a(n-29) +13*a(n-30) -1108*a(n-31) -394*a(n-32) +1467*a(n-33) +277*a(n-34) -1279*a(n-35) -39*a(n-36) +499*a(n-37) -358*a(n-38) -166*a(n-39) +499*a(n-40) +107*a(n-41) -216*a(n-42) +93*a(n-43) +202*a(n-44) -83*a(n-45) -170*a(n-46) +4*a(n-47) +71*a(n-48) -14*a(n-49) -46*a(n-50) -5*a(n-51) +13*a(n-52) +5*a(n-53) for n>55

Example

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

Crossrefs

Sequence in context: A218928 A202663 A202123 * A138973 A016177 A125427

Adjacent sequences: A201084 A201085 A201086 * A201088 A201089 A201090

Keyword

nonn

Author

R. H. Hardin Nov 26 2011

Status

approved