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 A214961 a(0)=a(1)=1, a(n) = least k>a(n-1) such that k*a(n-2) is a triangular number. 5
 1, 1, 3, 6, 7, 11, 13, 21, 25, 30, 49, 59, 97, 117, 193, 233, 385, 465, 492, 596, 983, 1191, 1965, 2381, 2516, 4761, 5031, 5761, 6290, 8466, 9795, 15470, 15867, 17403, 20559, 24170, 26945, 27192, 27755, 30130, 35235, 43537, 45100, 56805, 58717, 58739, 91000, 117477 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS PROG (Python) prpr = prev = 1 for n in range(1, 55):     print prpr,     b = k = 0     while k<=prev:         d = b*(b+1)/2         k = 0         if d%prpr==0:             k = d / prpr         b += 1     prpr = prev     prev = k CROSSREFS Cf. A214914, A214915, A214916, A214963, A213005. Sequence in context: A153033 A282167 A076644 * A189626 A297292 A087642 Adjacent sequences:  A214958 A214959 A214960 * A214962 A214963 A214964 KEYWORD nonn AUTHOR Alex Ratushnyak, Aug 03 2012 STATUS approved

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Last modified March 22 10:07 EDT 2019. Contains 321421 sequences. (Running on oeis4.)