login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A164661
Denominators of row sums of triangle of rationals A164658/A164659. Definite integral of Chebyshev polynomials of the first kind: Integral_{x=0..1} T(n,x).
7
1, 2, 3, 2, 15, 6, 35, 6, 63, 10, 99, 10, 143, 14, 195, 14, 255, 18, 323, 18, 399, 22, 483, 22, 575, 26, 675, 26, 783, 30, 899, 30, 1023, 34, 1155, 34, 1295, 38, 1443, 38, 1599, 42, 1763, 42, 1935, 46, 2115, 46, 2303, 50, 2499, 50, 2703, 54, 2915, 54, 3135, 58, 3363, 58, 3599
OFFSET
0,2
COMMENTS
The numerators are given in A164660.
See the W. Lang link under A164660 for a list of the first rationals.
FORMULA
a(n) = denominator(Sum_{m=1..n+1} IT(n,m)), n>=0, with IT(n,m):= A164658(n,m)/A164659(n,m) (coefficient triangle from the indefinite integral Integral_{x} T(n,x), n>=0, in lowest terms).
EXAMPLE
Rationals A164660(n)/a(n) = [1, 1/2, -1/3, -1/2, -1/15, 1/6, -1/35, -1/6, -1/63, 1/10, -1/99, ...].
CROSSREFS
Sequence in context: A181350 A174111 A367566 * A104507 A101033 A136454
KEYWORD
nonn,easy,frac
AUTHOR
Wolfdieter Lang, Oct 16 2009
STATUS
approved