A195464 a(n) = 2^(4*n + 3) + 2*4^n + 3.

13, 139, 2083, 32899, 524803, 8390659, 134225923, 2147516419, 34359869443, 549756338179, 8796095119363, 140737496743939, 2251799847239683, 36028797153181699, 576460752840294403, 9223372039002259459, 147573952598266347523, 2361183241469182345219

Offset

0,1

Comments

Binary numbers of form 1j1i11 where j and i are the number of 0's, n is the index, i = 2*n+1, j = 2*n+3.

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..800

Index entries for linear recurrences with constant coefficients, signature (21,-84,64).

Formula

a(n) = 2^(4*n+3) + A188161(n).

From Alexander R. Povolotsky, Sep 19 2011: (Start)

a(n+2) = 20*a(n+1) - 64*a(n) + 135.

G.f.: (-13 + 134*x - 256*x^2)/(-1 + 21*x - 84*x^2 + 64*x^3). (End)

a(n) = 3 + A026244(n+1). - Bruno Berselli, Sep 19 2011

Example

Terms starting from n=1 written in binary are 10001011, 100000100011, 1000000010000011, 10000000001000000011.

Prog

(Magma) [2^(4*n + 3) + 2*4^n + 3: n in [0..20]]; // Vincenzo Librandi, Sep 30 2011

Crossrefs

Cf. A188161.

Sequence in context: A351812 A300694 A193708 * A365999 A064103 A266630

Adjacent sequences: A195461 A195462 A195463 * A195465 A195466 A195467

Keyword

nonn,easy

Author

Brad Clardy, Sep 19 2011

Status

approved