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A119901
Difference between two consecutive squares enclosing 3^(2n+1).
0
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
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
KEYWORD
nonn
AUTHOR
Zak Seidov, May 27 2006
EXTENSIONS
Extended by Ray Chandler, Jun 09 2006
STATUS
approved