A160469 The left hand column of the triangle A160468.

1, 1, 2, 17, 62, 1382, 21844, 929569, 6404582, 443861162, 18888466084, 1936767361654, 58870668456604, 8374643517010684, 689005380505609448, 129848163681107301953, 1736640792209901647222, 418781231495293038913922

Offset

1,3

Comments

Resembles A002430, the numerators of the Taylor series for tan(x). The first difference occurs at a(12). (Its resemblance to 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 (which resembles the denominators of the Taylor series for tan(x)).

Sequence in context: A226417 A191295 A002430 * A176581 A303374 A357737

Adjacent sequences: A160466 A160467 A160468 * A160470 A160471 A160472

Keyword

easy,nonn

Author

Johannes W. Meijer, May 24 2009

Status

approved