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A072502
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Numbers that are run sums (trapezoidal, the difference between two triangular numbers) in exactly 3 ways.
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1
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9, 18, 25, 36, 49, 50, 72, 98, 100, 121, 144, 169, 196, 200, 242, 288, 289, 338, 361, 392, 400, 484, 529, 576, 578, 676, 722, 784, 800, 841, 961, 968, 1058, 1152, 1156, 1352, 1369, 1444, 1568, 1600, 1681, 1682, 1849, 1922, 1936, 2116, 2209, 2304, 2312, 2704
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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LINKS
| R. D. Knott Runsums
T. Verhoeff, Rectangular and Trapezoidal Arrangements, J. Integer Sequences, Vol. 2, 1999, #99.1.6.
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EXAMPLE
| a(1)=9 is the smallest number with 3 runsums: 2+3+4=4+5=9
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CROSSREFS
| Not to be confused with A069562. See A001227, A038547, A038550.
Sequence in context: A038837 A034046 A069562 * A195268 A102042 A121282
Adjacent sequences: A072499 A072500 A072501 * A072503 A072504 A072505
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KEYWORD
| easy,nonn
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AUTHOR
| Ron Knott (maths(AT)ronknott.com), Jan 27 2003
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EXTENSIONS
| Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Dec 30 2011
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