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 A301617 #28 Dec 14 2019 16:38:12 %S A301617 1,19,37,73,91,109,127,163,181,199,217,253,271,289,307,343,361,379, %T A301617 397,433,451,469,487,523,541,559,577,613,631,649,667,703,721,739,757, %U A301617 793,811,829,847,883,901,919,937,973,991,1009,1027,1063,1081,1099 %N A301617 Numbers not divisible by 2, 3 or 5 (A007775) with digital root 1. %C A301617 Numbers == {1, 19, 37, 73} mod 90 with additive sum sequence 1{+18+18+36+18} {repeat ...}. Includes all prime numbers > 7 with digital root 1. %H A301617 Colin Barker, <a href="/A301617/b301617.txt">Table of n, a(n) for n = 1..1000</a> %H A301617 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,1,-1). %F A301617 n == {1, 19, 37, 73} mod 90. %F A301617 a(n + 1) = a(n) + 18 * A177704(n + 1). - _David A. Corneth_, Mar 24 2018 %F A301617 From _Colin Barker_, Mar 24 2018: (Start) %F A301617 G.f.: x*(1 + 18*x + 18*x^2 + 36*x^3 + 17*x^4) / ((1 - x)^2*(1 + x)*(1 + x^2)). %F A301617 a(n) = a(n-1) + a(n-4) - a(n-5) for n>5. %F A301617 (End) %e A301617 1+18=19; 19+18=37; 37+36=73; 73+18=91; 91+18=109. %p A301617 seq(seq(i+90*j,i=[1,19,37,73]),j=0..30); # _Robert Israel_, Mar 25 2018 %t A301617 LinearRecurrence[{1,0,0,1,-1},{1,19,37,73,91},50] (* _Harvey P. Dale_, Dec 14 2019 *) %o A301617 (PARI) a(n) = 1 + 18 * (n - 1 + n\4) \\ _David A. Corneth_, Mar 24 2018 %o A301617 (PARI) Vec(x*(1 + 18*x + 18*x^2 + 36*x^3 + 17*x^4) / ((1 - x)^2*(1 + x)*(1 + x^2)) + O(x^60)) \\ _Colin Barker_, Mar 24 2018 %Y A301617 Cf. A177704, A045572. %Y A301617 Intersection of A007775 and A017173. %K A301617 nonn,base,easy %O A301617 1,2 %A A301617 _Gary Croft_, Mar 24 2018 %E A301617 The missing term 1081 added to the sequence by _Colin Barker_, Mar 24 2018