A119901 Difference between two consecutive squares enclosing 3^(2n+1).

3, 11, 31, 93, 281, 841, 2525, 7575, 22727, 68183, 204551, 613655, 1840965, 5522897, 16568691, 49706071, 149118215, 447354647, 1342063941, 4026191825, 12078575475, 36235726425, 108707179277, 326121537829, 978364613487

Offset

0,1

Links

Table of n, a(n) for n=0..24.

Formula

a(n) = 2*Floor(3^((2n + 1)/2)) + 1.

Example

a(2)=31 because 3^(2*2+1)=3^5=243, 15^2<243<16^2 and 16^2-15^2=256-225=31.

Mathematica

f[n_] := 2*Floor[3^((2n + 1)/2)] + 1; Table[f[n], {n, 0, 25}] (* Ray Chandler, Jun 09 2006 *)

Crossrefs

Sequence in context: A291887 A217323 A263781 * A106934 A146581 A146456

Adjacent sequences: A119898 A119899 A119900 * A119902 A119903 A119904

Keyword

nonn

Author

Zak Seidov, May 27 2006

Extensions

Extended by Ray Chandler, Jun 09 2006

Status

approved