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 A047345 Numbers that are congruent to {0, 4} mod 7. 14
 0, 4, 7, 11, 14, 18, 21, 25, 28, 32, 35, 39, 42, 46, 49, 53, 56, 60, 63, 67, 70, 74, 77, 81, 84, 88, 91, 95, 98, 102, 105, 109, 112, 116, 119, 123, 126, 130, 133, 137, 140, 144, 147, 151, 154, 158, 161, 165, 168, 172, 175, 179, 182, 186, 189, 193 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Nonnegative k such that k or 5*k + 1 is divisible by 7. - Bruno Berselli, Feb 13 2018 Maximum number of 2's possible in an infinite Minesweeper grid with n mines. The pattern of mines (x) that generates these 2's looks like "...xx.xx.xx...". - Dmitry Kamenetsky, Apr 14 2018 LINKS David Lovler, Table of n, a(n) for n = 1..1000 Wikipedia, Minesweeper. Index entries for linear recurrences with constant coefficients, signature (1,1,-1). FORMULA a(n) = ceiling(7*(n-1)/2). a(n) = 7*n - a(n-1) - 10 for n>1, a(1)=0. - Vincenzo Librandi, Aug 05 2010 From R. J. Mathar, Oct 08 2011: (Start) a(n) = 7*n/2 - 13/4 + (-1)^n/4. G.f.: x^2*(4 + 3*x) / ((1 + x)*(x - 1)^2). (End) a(n+1) = Sum_{k>=0} A030308(n,k)*b(k), with b(0) = 4, b(k) = A005009(k-1) = 7*2^(k-1), and k>0. - Philippe Deléham, Oct 17 2011. a(n) = 4*(n - 1) - floor((n - 1)/2). - Wesley Ivan Hurt, Jun 14 2013 a(n) = 2*(n - 1) + floor((3*n - 2 - (n mod 2))/2). - Wesley Ivan Hurt, Mar 31 2014 E.g.f.: 3 + ((14*x - 13)*exp(x) + exp(-x))/4. - David Lovler, Aug 31 2022 MAPLE A047345:=n->ceil(7*(n-1)/2); seq(A047345(n), n=1..100); # Wesley Ivan Hurt, Mar 31 2014 MATHEMATICA Table[Ceiling[7 (n - 1)/2], {n, 100}] (* Wesley Ivan Hurt, Mar 31 2014 *) PROG (PARI) forstep(n=0, 200, [4, 3], print1(n", ")) \\ Charles R Greathouse IV, Oct 17 2011 CROSSREFS Cf. A030123. Cf. A005009, A030308. Sequence in context: A190769 A083051 A198269 * A310728 A247157 A087070 Adjacent sequences: A047342 A047343 A047344 * A047346 A047347 A047348 KEYWORD nonn,easy AUTHOR N. J. A. Sloane STATUS approved

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Last modified June 24 07:41 EDT 2024. Contains 373663 sequences. (Running on oeis4.)