A128897 a(n) = ((2n)^(2n-1)+1)/(2n+1).

1, 13, 1111, 233017, 90909091, 57154490053, 52914318216943, 67818912035696881, 115047976828352449051, 249660952380952380952381, 674758650917429955329341351, 2222892961417140207415135788073

Offset

1,2

Links

Table of n, a(n) for n=1..12.

Formula

a(n) = ((2n)^(2n-1)+1)/(2n+1). a(n) = A083062(2n-1).

Crossrefs

Cf. A083062 ((n+1)^n/(n+2) - (-1)^n/(n+2)).

Sequence in context: A264249 A195890 A195520 * A201265 A221390 A226095

Adjacent sequences: A128894 A128895 A128896 * A128898 A128899 A128900

Keyword

nonn

Author

Alexander Adamchuk, Apr 20 2007

Status

approved