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 A195156 a(n) = (16^n-1)/3. 2
 0, 5, 85, 1365, 21845, 349525, 5592405, 89478485, 1431655765, 22906492245, 366503875925, 5864062014805, 93824992236885, 1501199875790165, 24019198012642645, 384307168202282325, 6148914691236517205, 98382635059784275285, 1574122160956548404565 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Numbers of A002450 that are multiples of 5. Also sequence found by reading the line from 0, in the direction 0, 5,..., in the square spiral whose edges are the Jacobsthal numbers A001045 and whose vertices are the numbers A000975. This is a semi-diagonal in the spiral. In binary, these numbers are 101...01 (see A031982). - Alonso del Arte, May 20 2017 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..800 Index entries for linear recurrences with constant coefficients, signature (17,-16). FORMULA From Bruno Berselli, Sep 19 2011: (Start) G.f.: 5*x/((1-x)*(1-16*x)). a(n) = A002450(2n) = (16^n-1)/3. a(n) = 5*A131865(n-1) = a(n-1) + 5*A001025(n-1) = 16*a(n-1) + 5 for n > 0. (End) MAPLE A195156:=n->(16^n-1)/3; seq(A195156(k), k=0..50); # Wesley Ivan Hurt, Oct 24 2013 MATHEMATICA Table[(16^n - 1)/3, {n, 0, 63}] (* Wesley Ivan Hurt, Oct 24 2013 *) PROG (MAGMA) [(16^n-1)/3:n in [0..20]]; // Vincenzo Librandi, Sep 20 2011 (PARI) for(n=0, 50, print1((16^n - 1)/3, ", ")) \\ G. C. Greubel, Oct 11 2017 CROSSREFS Bisection of A002450. Cf. A000975, A001045. Sequence in context: A201797 A012743 A139744 * A188918 A218139 A241330 Adjacent sequences:  A195153 A195154 A195155 * A195157 A195158 A195159 KEYWORD nonn,easy AUTHOR Omar E. Pol, Sep 10 2011 EXTENSIONS New sequence name suggested by Charles R Greathouse IV using Berselli's formula. - Sep 19 2011 STATUS approved

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Last modified September 17 19:16 EDT 2019. Contains 327137 sequences. (Running on oeis4.)