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A079610 (5*n+1)*(5*n+3)*(5*n+5). 1
15, 480, 2145, 5760, 12075, 21840, 35805, 54720, 79335, 110400, 148665, 194880, 249795, 314160, 388725, 474240, 571455, 681120, 803985, 940800, 1092315, 1259280, 1442445, 1642560, 1860375, 2096640, 2352105, 2627520, 2923635, 3241200, 3580965, 3943680 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

REFERENCES

R. Tijdeman, Some applications of Diophantine approximation, pp. 261-284 of Surveys in Number Theory (Urbana, May 21, 2000), ed. M. A. Bennett et al., Peters, 2003.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Index to sequences with linear recurrences with constant coefficients, signature (4,-6,4,-1).

FORMULA

Sum_{n>=0} 1/a(n) is transcendental (cf. Tijdeman).

G.f.: 15*(1+28*x+21*x^2)/(1-x)^4. [Colin Barker, Apr 28 2012]

a(n) = 4*a(n-1) -6*a(n-2) +4*a(n-3) -a(n-4). Vincenzo Librandi, Jun 23 2012

MATHEMATICA

Times@@@(#+{1, 3, 5}&/@(5*Range[0, 50])) (* Harvey P. Dale, Jan 01 2011 *)

LinearRecurrence[{4, -6, 4, -1}, {15, 480, 2145, 5760}, 40] (* Vincenzo Librandi, Jun 23 2012

PROG

(MAGMA) I:=[15, 480, 2145, 5760]; [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..40]]; // Vincenzo Librandi, Jun 23 2012

CROSSREFS

Sequence in context: A005815 A120600 A129892 * A218803 A218198 A208624

Adjacent sequences:  A079607 A079608 A079609 * A079611 A079612 A079613

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, Jan 28 2003

STATUS

approved

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Last modified December 20 11:26 EST 2014. Contains 252241 sequences.