A296287 Solution of the complementary equation a(n) = a(n-1) + a(n-2) + n*b(n-2), where a(0) = 2, a(1) = 3, b(0) = 1, and (a(n)) and (b(n)) are increasing complementary sequences.

2, 3, 7, 22, 49, 101, 198, 362, 640, 1101, 1861, 3105, 5134, 8434, 13792, 22481, 36561, 59365, 96286, 156050, 252796, 409350, 662696, 1072644, 1735988, 2809332, 4546074, 7356216, 11903158, 19260302, 31164450, 50425806, 81591376, 132018370, 213611004

Offset

0,1

Comments

The increasing complementary sequences a() and b() are uniquely determined by the titular equation and initial values. a(n)/a(n-1) -> (1 + sqrt(5))/2 = golden ratio (A001622). See A296245 for a guide to related sequences.

Links

Clark Kimberling, Table of n, a(n) for n = 0..1000

Clark Kimberling, Complementary equations, J. Int. Seq. 19 (2007), 1-13.

Example

a(0) = 2, a(1) = 3, b(0) = 1, b(1) = 4, b(2) = 5
a(2) = a(0) + a(1) + 2*b(0) = 7
Complement: (b(n)) = (1, 4, 5, 6, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 23, ...)

Mathematica

a[0] = 2; a[1] = 3; b[0] = 1;
a[n_] := a[n] = a[n - 1] + a[n - 2] + n*b[n-2];
j = 1; While[j < 10, k = a[j] - j - 1;
 While[k < a[j + 1] - j + 1, b[k] = j + k + 2; k++]; j++];
Table[a[n], {n, 0, k}]; (* A296287 *)
Table[b[n], {n, 0, 20}]    (* complement *)

Crossrefs

Cf. A001622, A296245.

Sequence in context: A109456 A155745 A067738 * A187014 A053966 A010738

Adjacent sequences: A296284 A296285 A296286 * A296288 A296289 A296290

Keyword

nonn,easy

Author

Clark Kimberling, Dec 14 2017

Status

approved