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A076458
Sum of numbers that can be written as t*n + u*(n+1) for nonnegative integers t,u in exactly five ways.
2
17, 165, 678, 1910, 4335, 8547, 15260, 25308, 39645, 59345, 85602, 119730, 163163, 217455, 284280, 365432, 462825, 578493, 714590, 873390, 1057287, 1268795, 1510548, 1785300, 2095925, 2445417, 2836890, 3273578, 3758835, 4296135, 4889072, 5541360
OFFSET
1,1
REFERENCES
Fred. Schuh, Vragen betreffende een onbepaalde vergelijking, Nieuw Tijdschrift voor Wiskunde, 52 (1964-1965) 193-198.
LINKS
FORMULA
a(n) = n*(n+1)*(10*n^2+8*n-1)/2.
G.f.: x*(17+80*x+23*x^2)/(1-x)^5.
MAPLE
seq(1/2*n*(n+1)*(10*n^2+8*n-1), n=1..40);
MATHEMATICA
CoefficientList[Series[(17 + 80 x + 23 x^2)/(1 - x)^5, {x, 0, 50}], x] (* Vincenzo Librandi, Dec 30 2013 *)
PROG
(Magma) [n*(n+1)*(10*n^2+8*n-1)/2: n in [1..50]]; // Vincenzo Librandi, Dec 30 2013
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Floor van Lamoen, Oct 13 2002
EXTENSIONS
More terms from Vincenzo Librandi, Dec 30 2013
STATUS
approved