A125054 - OEIS

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A125054

Central terms of triangle A125053.

1, 3, 21, 327, 9129, 396363, 24615741, 2068052367, 225742096209, 31048132997523, 5252064083753061, 1071525520294178007, 259439870666594250489, 73542221109962636293083, 24125551094579137082039181 (list; graph; refs; listen; history; internal format)

	OFFSET	`0,2`
	COMMENTS	`Triangle A125053 is a variant of triangle A008301 (enumeration of binary trees) such that the left-most column is the secant numbers (A000364).`
	FORMULA	`Binomial transform of A000182 (e.g.f. tan(x)).` `a(n)=Sum_{k, 0<=k<=n}A130847(n,k)*2^k. - Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Jul 22 2007`
	CROSSREFS	`Cf. A125053, A125055.` `Sequence in context: A005329 A134528 A118410 * A113085 A083228 A186271` `Adjacent sequences: A125051 A125052 A125053 * A125055 A125056 A125057`
	KEYWORD	`nonn`
	AUTHOR	`Paul D. Hanna (pauldhanna(AT)juno.com), Nov 21 2006`

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Last modified February 17 12:23 EST 2012. Contains 206011 sequences.