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 A163662 A020988 written in base 2. 4
 10, 1010, 101010, 10101010, 1010101010, 101010101010, 10101010101010, 1010101010101010, 101010101010101010, 10101010101010101010, 1010101010101010101010, 101010101010101010101010, 10101010101010101010101010, 1010101010101010101010101010 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The digits are n concatenated blocks of (10). Smallest number having alternating bit sum -n. Cf. A065359. - Washington Bomfim, Jan 22 2011 LINKS G. C. Greubel, Table of n, a(n) for n = 1..495 Index entries for linear recurrences with constant coefficients, signature (101, -100). FORMULA a(n) = Sum_{k=1,...,n} 10^(2k-1). From R. J. Mathar, Jul 08 2009: (Start) a(n) = 100*a(n-1) + 10. a(n) = 101*a(n-1) - 100*a(n-2). G.f.: 10*x/((100*x-1)*(x-1)). (End) From G. C. Greubel, Aug 01 2017: (Start) a(n) = (10/99)*(10^(2*n) - 1). E.g.f.: (10/99)*(exp(100*x) - exp(x)). (End) MAPLE A163662 := proc(n) add(10^(2*k-1), k=1..n) ; end: seq(A163662(n), n=1..30) ; # R. J. Mathar, Jul 08 2009 MATHEMATICA Table[(10/99)*(10^(2*n) - 1), {n, 1, 50}] (* G. C. Greubel, Aug 01 2017 *) Table[FromDigits[PadRight[{}, 2n, {1, 0}]], {n, 20}] (* or *) LinearRecurrence[ {101, -100}, {10, 1010}, 20] (* Harvey P. Dale, Jan 08 2020 *) PROG (PARI) x='x+O('x^50); Vec(10*x/((100*x-1)*(x-1))) \\ G. C. Greubel, Aug 01 2017 CROSSREFS Sequence in context: A075171 A106456 A079214 * A176067 A080070 A303610 Adjacent sequences:  A163659 A163660 A163661 * A163663 A163664 A163665 KEYWORD nonn,base,easy AUTHOR Jaroslav Krizek, Aug 02 2009 STATUS approved

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Last modified July 31 06:15 EDT 2021. Contains 346369 sequences. (Running on oeis4.)