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A261241 One half of numbers representable in at least two different ways as sums of four nonvanishing cubes. See A259060 for these numbers and their representations. 1
3213, 3950, 4807, 5796, 6929, 8218, 9675, 11312, 13141, 15174, 17423, 19900, 22617, 25586, 28819, 32328, 36125, 40222, 44631, 49364, 54433, 59850, 65627, 71776, 78309, 85238, 92575, 100332, 108521, 117154, 126243, 135800, 145837, 156366 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,1
COMMENTS
See A259060. There may be other numbers with this property.
REFERENCES
W. Sierpiński, 250 Problems in Elementary Number Theory, American Elsevier Publ. Comp., New York, PWN-Polish Scientific Publishers, Warszawa, 1970, Problem 227, p. 20 and p. 110.
LINKS
FORMULA
a(n) = (n+9)*(2*n^2 + 36*n + 357), n >= 0.
O.g.f.: (3213 - 8902*x + 8285*x^2 - 2584*x^3)/(1-x)^4.
a(n) = 4*a(n-1)-6*a(n-2)+4*a(n-3)-a(n-4). - Vincenzo Librandi, Aug 13 2015
MATHEMATICA
CoefficientList[Series[(3213 - 8902 x + 8285 x^2 - 2584 x^3)/(1 - x)^4, {x, 0, 50}], x] (* Vincenzo Librandi, Aug 13 2015 *)
PROG
(Magma) [(n+9)*(2*n^2 + 36*n + 357): n in [0..50]] /* or */ I:=[3213, 3950, 4807, 5796]; [n le 4 select I[n] else 4*Self(n-1)-6*Self(n-2)+4*Self(n-3)-Self(n-4): n in [1..50]]; // Vincenzo Librandi, Aug 13 2015
CROSSREFS
Cf. A259060.
Sequence in context: A048255 A303995 A091329 * A345772 A020414 A202612
KEYWORD
nonn,easy
AUTHOR
Wolfdieter Lang, Aug 12 2015
STATUS
approved

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Last modified July 12 11:04 EDT 2024. Contains 374244 sequences. (Running on oeis4.)