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 A248474 #28 May 22 2025 10:21:40
%S A248474 13,17,43,47,73,77,103,107,133,137,163,167,193,197,223,227,253,257,
%T A248474 283,287,313,317,343,347,373,377,403,407,433,437,463,467,493,497,523,
%U A248474 527,553,557,583,587,613,617,643,647,673,677,703,707,733,737,763,767,793,797
%N A248474 Numbers congruent to 13 or 17 mod 30.
%C A248474 The combination of A082369(30*n+13) and A128468(30*n+17) is the base sequence for A140533(Primes congruent to 13 or 17 mod 30).
%H A248474 Karl V. Keller, Jr., <a href="/A248474/b248474.txt">Table of n, a(n) for n = 1..10000</a>
%H A248474 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (1,1,-1).
%F A248474 From _Colin Barker_, Oct 07 2014: (Start)
%F A248474 a(n) = (-15-11*(-1)^n+30*n)/2.
%F A248474 a(n) = a(n-1)+a(n-2)-a(n-3).
%F A248474 G.f.: x*(13*x^2+4*x+13) / ((x-1)^2*(x+1)). (End)
%F A248474 E.g.f.: 13 + ((30*x - 15)*exp(x) - 11*exp(-x))/2. - _David Lovler_, Sep 10 2022
%F A248474 Sum_{n>=1} (-1)^(n+1)/a(n) = (sqrt(2*(5+sqrt(5)))+sqrt(3)-sqrt(15))*Pi / (30*(sqrt(6*(5+sqrt(5)))+sqrt(5)-1)). - _Amiram Eldar_, Jul 30 2024
%t A248474 Flatten[Table[{15n - 2, 15n + 2}, {n, 1, 41, 2}]] (* _Alonso del Arte_, Oct 06 2014 *)
%o A248474 (Python)
%o A248474 for n in range(1,101):
%o A248474 print (n*30-17),
%o A248474 print (n*30-13),
%o A248474 (PARI)
%o A248474 Vec(x*(13*x^2+4*x+13)/((x-1)^2*(x+1)) + O(x^100)) \\ _Colin Barker_, Oct 07 2014
%Y A248474 Cf. A082369 (30*n+13), A128468 (30*n+17).
%Y A248474 Cf. A039949 (Primes of the form 30n-13), A132233 (Primes congruent to 13 mod 30), A140533 (Primes congruent to 13 or 17 mod 30).
%K A248474 nonn,easy
%O A248474 1,1
%A A248474 _Karl V. Keller, Jr._, Oct 06 2014