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A296268
Solution of the complementary equation a(n) = a(n-1) + a(n-2) + b(n-2)*b(n), where a(0) = 1, a(1) = 4, b(0) = 2, b(1) = 3, b(2) = 5, and (a(n)) and (b(n)) are increasing complementary sequences.
2
1, 4, 15, 37, 87, 172, 322, 574, 995, 1689, 2827, 4684, 7719, 12641, 20648, 33612, 54620, 88631, 143691, 232805, 377024, 610404, 988052, 1599131, 2587911, 4187825, 6776576, 10965300, 17742836, 28709159, 46453083, 75163397, 121617704, 196782431, 318401539
OFFSET
0,2
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) = 1, a(1) = 4, b(0) = 2, b(1) = 3, b(2) = 5;
a(2) = a(0) + a(1) + b(0)*b(2) = 15;
Complement: (b(n)) = (2, 3, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16, 17, ...)
MATHEMATICA
a[0] = 1; a[1] = 4; b[0] = 2; b[1] = 3; 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}]; (* A296268 *)
Table[b[n], {n, 0, 20}] (* complement *)
CROSSREFS
Sequence in context: A212974 A033813 A296295 * A209409 A241302 A112666
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Dec 12 2017
STATUS
approved