

A295140


Solution of the complementary equation a(n) = 3*a(n2)  b(n2) + 4, where a(0) = 1, a(1) = 3, b(0) = 2, b(1) = 4, and (a(n)) and (b(n)) are increasing complementary sequences.


2



1, 3, 5, 9, 13, 24, 35, 66, 98, 190, 284, 559, 840, 1664, 2506, 4977, 7502, 14914, 22488, 44723, 67443, 134147, 202306, 402417, 606893, 1207225, 1820652, 3621647, 5461927, 10864911, 16385749, 32594700, 49157213, 97784065, 147471603, 293352158
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OFFSET

0,2


COMMENTS

The increasing complementary sequences a() and b() are uniquely determined by the titular equation and initial values. See A295053 for a guide to related sequences.
The sequence a(n+1)/a(n) appears to have two convergent subsequences, with limits 1.40..., 2.13...


LINKS



EXAMPLE

a(0) = 1, a(1) = 3, b(0) = 2, b(1) = 4
a(2) =3*a(0)  b(0) + 4 = 5
Complement: (b(n)) = (2, 4, 6, 7, 8, 10, 11, 12, 14, 15, 16, ...)


MATHEMATICA

mex := First[Complement[Range[1, Max[#1] + 1], #1]] &;
a[0] = 1; a[1] = 3; b[0] = 2; b[1]=4;
a[n_] := a[n] = 3 a[n  2] + b[n  2] + 4;
b[n_] := b[n] = mex[Flatten[Table[Join[{a[n]}, {a[i], b[i]}], {i, 0, n  1}]]];
Table[a[n], {n, 0, 18}] (* A295140 *)
Table[b[n], {n, 0, 10}]


CROSSREFS



KEYWORD

nonn,easy


AUTHOR



STATUS

approved



