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A296271
Solution of the complementary equation a(n) = a(n-1) + a(n-2) + b(n-2)*b(n), where a(0) = 3, a(1) = 4, b(0) = 1, b(1) = 2, b(2) = 5, and (a(n)) and (b(n)) are increasing complementary sequences.
2
3, 4, 12, 28, 75, 151, 289, 520, 908, 1558, 2620, 4373, 7217, 11845, 19350, 31518, 51228, 83145, 134813, 218441, 353782, 572798, 927204, 1500677, 2428635, 3930122, 6359656, 10290738, 16651417, 26943243, 43595815, 70540282, 114137392, 184679042, 298817877
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, Complementary equations, J. Int. Seq. 19 (2007), 1-13.
EXAMPLE
a(0) = 3, a(1) = 4, b(0) = 1, b(1) = 2, b(2) = 5;
a(2) = a(0) + a(1) + b(0)*b(2) = 11;
Complement: (b(n)) = (1, 2, 5, 6, 7, 8, 9, 10, 11, 13, 14, 15, 16, ...)
MATHEMATICA
a[0] = 3; a[1] = 4; b[0] = 1; b[1] = 2; b[2] = 5;
a[n_] := a[n] = a[n - 1] + a[n - 2] + b[n - 2] b[n];
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}]; (* A296271 *)
Table[b[n], {n, 0, 20}] (* complement *)
CROSSREFS
Sequence in context: A090660 A288140 A287594 * A000208 A079154 A101716
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Dec 12 2017
STATUS
approved