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 A169902 Earliest sequence such that xy | a(x+y) and (x+y) | a(xy) for all x >= 1, y >= 1. 1
 2, 3, 4, 60, 12, 2520, 120, 5040, 2520, 277200, 2520, 4324320, 27720, 5045040, 10810800, 49008960, 720720, 4190266080, 12252240, 4655851200, 4888643760, 117793035360, 232792560, 642507465600, 26771144400, 2088149263200 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Charlie Neder, Table of n, a(n) for n = 1..1000 PROG (Python) from math import gcd for n in range(1, 1001): ..a_n = 1 ..res = [] ..for addend in range(1, n//2+1): res.append(addend*(n - addend)) ..for dividend in range(1, n+1): ....if not n%dividend: res.append(dividend + n//dividend) ....if dividend*dividend >= n: break ..for i in res: a_n *= i // gcd(a_n, i) ..print(n, a_n) # Charlie Neder, Oct 09 2018 CROSSREFS Sequence in context: A282034 A096782 A098811 * A004855 A097930 A012322 Adjacent sequences: A169899 A169900 A169901 * A169903 A169904 A169905 KEYWORD nonn,nice AUTHOR Andrew Weimholt, Jul 05 2010 STATUS approved

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Last modified December 9 10:52 EST 2023. Contains 367690 sequences. (Running on oeis4.)