The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A263614 a(2n) = A000125(n), a(2n+1) = 2*a(2n). 2
 0, 0, 1, 2, 2, 4, 4, 8, 8, 16, 15, 30, 26, 52, 42, 84, 64, 128, 93, 186, 130, 260, 176, 352, 232, 464, 299, 598, 378, 756, 470, 940, 576, 1152, 697, 1394, 834, 1668, 988, 1976, 1160, 2320, 1351, 2702, 1562, 3124, 1794, 3588, 2048, 4096, 2325, 4650, 2626, 5252, 2952, 5904, 3304, 6608, 3683, 7366 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 COMMENTS For n >= 2, number of palindromic squares of length n whose decimal digits are 0 or 1 and with 9 or fewer 1's. LINKS Colin Barker, Table of n, a(n) for n = 0..1000 G. J. Simmons, Palindromic powers, J. Rec. Math., 3 (No. 2, 1970), 93-98. [Annotated scanned copy] Index entries for linear recurrences with constant coefficients, signature (0,4,0,-6,0,4,0,-1). FORMULA From Colin Barker, Oct 26 2015: (Start) a(n) = (-((-1)^n*(-78+62*n-12*n^2+n^3))+3*(-26+42*n-8*n^2+n^3))/96. a(n) = 4*a(n-2)-6*a(n-4)+4*a(n-6)-a(n-8) for n>7. G.f.: x^2*(2*x+1)*(2*x^4-2*x^2+1) / ((x-1)^4*(x+1)^4). (End) PROG (PARI) a(n) = (-((-1)^n*(-78+62*n-12*n^2+n^3))+3*(-26+42*n-8*n^2+n^3))/96 \\ Colin Barker, Oct 26 2015 (PARI) concat(vector(2), Vec(x^2*(2*x+1)*(2*x^4-2*x^2+1)/((x-1)^4*(x+1)^4) + O(x^100))) \\ Colin Barker, Oct 26 2015 CROSSREFS Cf. A000125, A263615. Sequence in context: A344607 A325722 A279818 * A082267 A338739 A076939 Adjacent sequences: A263611 A263612 A263613 * A263615 A263616 A263617 KEYWORD nonn,base,easy AUTHOR N. J. A. Sloane, Oct 23 2015 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 June 4 21:13 EDT 2023. Contains 363130 sequences. (Running on oeis4.)