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A093412 Triangle read by rows: a(n, k) is the numerator of (n + (n-1) + ... + (n-k+1))/(1 + 2 + ... + k), 0 < k <= n. 8
1, 2, 1, 3, 5, 1, 4, 7, 3, 1, 5, 3, 2, 7, 1, 6, 11, 5, 9, 4, 1, 7, 13, 3, 11, 5, 9, 1, 8, 5, 7, 13, 2, 11, 5, 1, 9, 17, 4, 3, 7, 13, 3, 11, 1, 10, 19, 9, 17, 8, 15, 7, 13, 6, 1, 11, 7, 5, 19, 3, 17, 2, 5, 7, 13, 1, 12, 23, 11, 21, 10, 19, 9, 17, 8, 15, 7, 1, 13, 25, 6, 23, 11, 3, 5, 19, 9, 17, 4 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

A093415 gives the corresponding denominators.

LINKS

Table of n, a(n) for n=1..89.

FORMULA

a(n, k) = (2n+1-k)/gcd(2n+1-k, k+1).

EXAMPLE

Triangle a(n,k) (with rows n >= 1 and columns k >= 1) begins as follows:

  1;

  2,  1;

  3,  5, 1;

  4,  7, 3,  1;

  5,  3, 2,  7, 1;

  6, 11, 5,  9, 4,  1;

  7, 13, 3, 11, 5,  9, 1;

  8,  5, 7, 13, 2, 11, 5,  1;

  9, 17, 4,  3, 7, 13, 3, 11, 1;

... - Petros Hadjicostas, Oct 20 2019

CROSSREFS

Cf. A093413, A093414, A093415.

Sequence in context: A062105 A210563 A236311 * A119355 A076110 A117584

Adjacent sequences:  A093409 A093410 A093411 * A093413 A093414 A093415

KEYWORD

easy,nonn,tabl,frac

AUTHOR

Amarnath Murthy, Mar 30 2004

EXTENSIONS

Edited and extended by David Wasserman, Feb 01 2006

STATUS

approved

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Last modified September 18 09:22 EDT 2020. Contains 337166 sequences. (Running on oeis4.)