The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A036257 Number of inequivalent strings of 2n digits, when 2 strings are equivalent if turning 1 upside down gives the other. 3
 1, 90, 9700, 992250, 99805000, 9995118750, 999877937500, 99996948281250, 9999923706250000, 999998092652343750, 99999952316289062500, 9999998807907128906250, 999999970197677734375000, 99999999254941940917968750, 9999999981373548510742187500 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 REFERENCES N. G. de Bruijn, Polya's theory of counting, in Beckenbach, ed., Applied Combinatorial Math., Wiley, 1964 (p. 182). J.-P. Delahaye, 'Le miraculeux "lemme de Burnside"','La bande de chiffres' pp 146 in 'Pour la Science' (French edition of 'Scientific American') No.350 December 2006 Paris. LINKS Colin Barker, Table of n, a(n) for n = 0..400 Index entries for linear recurrences with constant coefficients, signature (130,-3125,12500). FORMULA a(n) = 10^(2*n) - 5^(2*n)/2 + 5^n/2. From Colin Barker, Jul 03 2017: (Start) G.f.: (1 - 40*x + 1125*x^2) / ((1 - 5*x)*(1 - 25*x)*(1 - 100*x)). a(n) = 130*a(n-1) - 3125*a(n-2) + 12500*a(n-3) for n>2. (End) PROG (PARI) Vec((1 - 40*x + 1125*x^2) / ((1 - 5*x)*(1 - 25*x)*(1 - 100*x)) + O(x^30)) \\ Colin Barker, Jul 03 2017 CROSSREFS Cf. A036255, A036258. Sequence in context: A166822 A166804 A116273 * A276352 A203779 A359842 Adjacent sequences: A036254 A036255 A036256 * A036258 A036259 A036260 KEYWORD nonn,easy,base AUTHOR N. J. A. Sloane STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified May 18 12:18 EDT 2024. Contains 372630 sequences. (Running on oeis4.)