This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A138987 #30 Apr 06 2025 18:25:28
%S A138987 1,2,3,4,5,6,15,17,19,21,23,25,41,44,47,50,53,56,79,83,87,91,95,99,
%T A138987 129,134,139,144,149,154,191,197,203,209,215,221,265,272,279,286,293,
%U A138987 300,351,359,367,375,383,391,449,458,467,476,485,494,559,569,579,589,599
%N A138987 a(n) = Frobenius number for 7 successive numbers = F(n+1, n+2, n+3, n+4, n+5, n+6, n+7).
%H A138987 Harvey P. Dale, <a href="/A138987/b138987.txt">Table of n, a(n) for n = 1..1000</a>
%H A138987 <a href="/index/Rec#order_13">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,0,0,2,-2,0,0,0,0,-1,1).
%F A138987 G.f.: x*(x^12-7*x^6-x^5-x^4-x^3-x^2-x-1) / ((x-1)^3*(x+1)^2*(x^2-x+1)^2*(x^2+x+1)^2). [_Colin Barker_, Dec 13 2012]
%F A138987 a(n) = n + (n+1)*floor((n-1)/6). - _Giorgos Kalogeropoulos_, Apr 06 2025
%e A138987 a(7) = 15 because 15 is the largest number k such that the equation 8*x_1 + 9*x_2 + 10*x_3 + 11*x_4 + 12*x_5 + 13*x_6 + 14*x_7 = k has no solution for any nonnegative x_i (in other words, for every k > 15 there exist one or more solutions).
%t A138987 Table[FrobeniusNumber[{n+1, n+2, n+3, n+4, n+5, n+6, n+7}], {n, 1, 100}]
%t A138987 Table[FrobeniusNumber[n+Range[7]],{n,100}] (* _Harvey P. Dale_, Dec 06 2021 *)
%t A138987 Table[n + Floor[(n-1)/6]*(n+1), {n, 100}] (* _Giorgos Kalogeropoulos_, Apr 06 2025 *)
%Y A138987 Frobenius number for k successive numbers: A028387 (k=2), A079326 (k=3), A138984 (k=4), A138985 (k=5), A138986 (k=6), this sequence (k=7), A138988 (k=8).
%K A138987 nonn,easy
%O A138987 1,2
%A A138987 _Artur Jasinski_, Apr 05 2008