A108142 a[1] = 1; a[2] = 1; a[3] = 1; a[4] = 1; a[5] = 1; a[6] = 1; for n >= 7, a[n] = 6*a[n - 1] - 5*a[n - 2] - 4*a[n - 3] - 3*a[ n - 4] + 2*a[n - 5] + a[n - 6]; then take absolute values.

1, 1, 1, 1, 1, 1, 3, 27, 151, 759, 3679, 17599, 83767, 397943, 1889059, 8964891, 42539855, 201849743, 957752095, 4544385823, 21562354767, 102309686479, 485441784803, 2303337053819, 10928934112423, 51855892302151

Offset

1,7

Comments

The 2nd countdown sequence.

References

Roger Bagula, Factoring Double Fibonacci Sequences, 2000

Links

Table of n, a(n) for n=1..26.

Index entries for linear recurrences with constant coefficients, signature (6, -5, -4, -3, 2, 1).

Mathematica

F[1] = 1; F[2] = 1; F[3] = 1; F[4] = 1; F[5] = 1; F[6] = 1; F[n__] := F[n] = 6*F[n - 1] - 5*F[n - 2] - 4*F[n - 3] - 3*F[ n - 4] + 2*F[n - 5] + F[n - 6] a = Table[Abs[F[n]], {n, 1, 50}]
LinearRecurrence[{6, -5, -4, -3, 2, 1}, {1, 1, 1, 1, 1, 1, 3, 27, 151, 759, 3679, 17599}, 30] (* Harvey P. Dale, Apr 25 2018 *)

Crossrefs

Cf. A056015, A056016.

Sequence in context: A341566 A354655 A127509 * A056263 A026093 A215711

Adjacent sequences: A108139 A108140 A108141 * A108143 A108144 A108145

Keyword

nonn

Author

Roger L. Bagula, Jun 05 2005

Extensions

Edited by N. J. A. Sloane, Jun 08 2007

Status

approved