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

Author

Johannes W. Meijer, May 24 2009

Keywords

• easy
• nonn

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).)

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)).

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, ....