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 A273416 Numbers that occur 5 or more times in the triangle of denominators in Leibniz's Harmonic Triangle. 0
 30, 1260, 1980, 74256, 1861860, 603380175840 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Of the first 6 terms the number 30 occurs 5 times, the others occur 6 times. a(6) = 603380175840 is not an oblong number. LINKS Table of n, a(n) for n=1..6. EXAMPLE The number 30 appears 1 time in row 5 in the central position {5*C(4,2)}, 2 times in row 6 {6*C(5,1); 6*C(5,4)} and, trivially, 2 times in row 30 {30*C(29,0); 30*C(29,29)}. The number 1260 appears 2 times in row 10 {10*C(9,4); 10*C(9,5)}, 2 times in row 36 {36*C(35,1); 36*C(35,34)} and, trivially, 2 times in row 1260 {1260*C(1259,0); 1260*C(1259,1259)}. CROSSREFS Cf. A003506. Sequence in context: A060076 A174716 A163521 * A002456 A358163 A107768 Adjacent sequences: A273413 A273414 A273415 * A273417 A273418 A273419 KEYWORD nonn,more AUTHOR Gionata Neri, May 22 2016 STATUS approved

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Last modified March 3 00:46 EST 2024. Contains 370499 sequences. (Running on oeis4.)