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 A335155 #12 Jun 07 2020 08:14:51 %S A335155 1,3,6,8,9,11,13,14,16,18,19,21,23,24,26,27,28,29,31,32,33,34,36,37, %T A335155 38,39,41,42,43,44,46,47,48,49,51,52,53,54,56,57,58,59,61,62,63,64,66, %U A335155 67,68,69,71,72,73,74,76,77,78,79,81,82,83,84,86,87,88,89,91,92,93,94,96,97,98,99,101,102,103,104,106 %N A335155 Start with 1; if n is in the sequence, so are n+5 and 3*n. %C A335155 This is the lexicographically earliest sequence of positive numbers with the property that if n is in the sequence, so are n+5 and 3*n. %C A335155 Suggested by A335365 (which is the complement). %H A335155 Colin Barker, <a href="/A335155/b335155.txt">Table of n, a(n) for n = 1..1000</a> %H A335155 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,1,-1). %F A335155 From _Colin Barker_, Jun 07 2020: (Start) %F A335155 G.f.: x*(1 + 2*x + 3*x^2 + 2*x^3 - x^6 - x^7 + x^8 - x^10 + x^11 - x^13 + x^14 - x^15 - x^16) / ((1 - x)^2*(1 + x)*(1 + x^2)). %F A335155 a(n) = a(n-1) + a(n-4) - a(n-5) for n>17. %F A335155 (End) %o A335155 (PARI) Vec(x*(1 + 2*x + 3*x^2 + 2*x^3 - x^6 - x^7 + x^8 - x^10 + x^11 - x^13 + x^14 - x^15 - x^16) / ((1 - x)^2*(1 + x)*(1 + x^2)) + O(x^60)) \\ _Colin Barker_, Jun 07 2020 %Y A335155 Cf. A335365. %Y A335155 See also A005658, A005660, A005662, etc. %K A335155 nonn,easy %O A335155 1,2 %A A335155 _N. J. A. Sloane_, Jun 05 2020