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A076456
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Sum of numbers that can be written as t*n + u*(n+1) for nonnegative integers t,u in exactly three ways.
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0
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9, 93, 390, 1110, 2535, 5019, 8988, 14940, 23445, 35145, 50754, 71058, 96915, 129255, 169080, 217464, 275553, 344565, 425790, 520590, 630399, 756723, 901140, 1065300, 1250925, 1459809, 1693818, 1954890, 2245035, 2566335, 2920944
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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REFERENCES
| Fred. Schuh, Vragen betreffende een onbepaalde vergelijking, Nieuw Tijdschrift voor Wiskunde, 52 (1964-1965) 193-198.
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FORMULA
| 1/2*n*(n+1)*(6*n^2+4*n-1). G.f.: 3*x*(5*x^2+16*x+3)/((1+x)*(1-x)^5).
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MAPLE
| seq(1/2*n*(n+1)*(6*n^2+4*n-1), n=1..40);
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CROSSREFS
| Cf. A002417, A076454-A076459.
Sequence in context: A007403 A015587 A024117 * A082724 A061635 A163951
Adjacent sequences: A076453 A076454 A076455 * A076457 A076458 A076459
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KEYWORD
| easy,nonn
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AUTHOR
| Floor van Lamoen (fvlamoen(AT)hotmail.com), Oct 13 2002
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