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 A105099 Nonnegative numbers n such that 23*n^2 + 23*n + 1 = j^2 = a square. 1
 0, 335, 815, 772320, 1877280, 1777881455, 4321498895, 4092682338240, 9948088580160, 9421352964748175, 22900495590030575, 21687950432167961760, 52716930900161804640, 49925652473497683224495, 121354352031676884251855 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS a(5)=2649601*(2*a(1)+1)-1-a(4), a(6)=2649601*(2*a(2)+1)-1-a(3), a(7)=2649601*(2*a(3)+1)-1-a(2), a(8)=2649601*(2*a(4)+1)-1-a(1), a(9)=2649601*(2*a(5)+1)-1-a(1), a(10)=2649601*(2*a(6)+1)-1-a(2), a(11)=2649601*(2*a(7)+1)-1-a(3), a(12)=2649601*(2*a(8)+1)-1-a(4), a(13)=2649601*(2*a(9)+1)-1-a(1), a(14)=2649601*(2*a(10)+1)-1-a(1). This is a strange recurrence - does it continue ? Remark : 2649601 = 23*24*25*192+1 In terms of indices of triangular numbers: A000217(n) = 4*A000217[(j-1)/2]/23. - R. J. Mathar, Dec 05 2007 LINKS Harvey P. Dale, Table of n, a(n) for n = 1..595 Index entries for linear recurrences with constant coefficients, signature (1,2302,-2302,-1,1). FORMULA Union of two sequences defined by the recurrence a(n+1)=2302*a(n)-a(n-1)+1150 a(0)=0, a(1)=335, a(2)=772320, ... a(0)=0, a(1)=815, a(2)=1877280, ... - Max Alekseyev, Apr 09 2005 O.g.f.: -5*(67*x^2+96*x+67)*x^2/((x^2+48*x+1)*(x^2-48*x+1)*(-1+x)). - R. J. Mathar, Dec 05 2007 MATHEMATICA LinearRecurrence[{1, 2302, -2302, -1, 1}, {0, 335, 815, 772320, 1877280}, 20] (* Harvey P. Dale, May 20 2021 *) CROSSREFS Sequence in context: A046015 A184076 A253227 * A038648 A224533 A253346 Adjacent sequences:  A105096 A105097 A105098 * A105100 A105101 A105102 KEYWORD nonn,easy AUTHOR Pierre CAMI, Apr 07 2005 EXTENSIONS More terms from Max Alekseyev, Apr 09 2005 More terms from R. J. Mathar, Dec 05 2007 STATUS approved

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Last modified June 25 03:59 EDT 2022. Contains 354835 sequences. (Running on oeis4.)