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A160469 A 'look-a-like' of the numerators in Taylor series for tan(x) 9
1, 1, 2, 17, 62, 1382, 21844, 929569, 6404582, 443861162, 18888466084, 1936767361654, 58870668456604, 8374643517010684, 689005380505609448, 129848163681107301953, 1736640792209901647222, 418781231495293038913922 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

This sequence makes its appearance as the first left hand column of 'triangle' A160468.

The first difference with the sequence for the numerators in the Taylor series for tan(x) A002430 occurs at a(12). Its resemblance with this sequence led to the conjecture A160469(n) = A002430(n)*A089170(n-1).

LINKS

Table of n, a(n) for n=1..18.

FORMULA

a(n) = A002430(n)*A089170(n-1) with A002430 (n) = numer((-1)^(n-1)*2^(2*n)*(2^(2*n)-1)* bernoulli(2*n)/(2*n)!) and A089170 (n-1) = numer(2*bernoulli(2*n)* (4^n-1)/(2*n))/ numer((4^n-1)*bernoulli(2*n)/(2*n)!) for n = 1, 2, 3, .. .\

CROSSREFS

Equals the first left hand column of A160468.

Equals A002430(n)*A089170(n-1).

Equals (A002430(n)/A036279(n))*(A117972(n)/A000265(n)).

Equals A048896(n-1)*A002425(n).

Cf. A156769 A 'look-a-like' of the denominators in Taylor series for tan(x).

Sequence in context: A226417 A191295 A002430 * A176581 A037420 A034721

Adjacent sequences:  A160466 A160467 A160468 * A160470 A160471 A160472

KEYWORD

easy,nonn

AUTHOR

Johannes W. Meijer, May 24 2009

STATUS

approved

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Last modified October 23 10:41 EDT 2014. Contains 248461 sequences.