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 A209205 #13 Mar 31 2012 10:28:59
%S A209205 144,1494,1740,2040,3324,4044,6420,12804,13260,13464,13620,15444,
%T A209205 25824,31524,31674,31680,32124,33720,38064,40410,44634,45804,46260,
%U A209205 51810,54510,56100,58914,60810,68004,69114,70794,74574,76050,77694,80580,81510,82434,89244
%N A209205 Values of the difference d for 6 primes in geometric-arithmetic progression with the minimal sequence {7*7^j + j*d}, j = 0 to 5.
%C A209205 A geometric-arithmetic progression of primes is a set of k primes (denoted by GAP-k) of the form p r^j + j d for fixed p, r and d and consecutive j. Symbolically, for r = 1, this sequence simplifies to the familiar primes in arithmetic progression (denoted by AP-k). The computations were done without any assumptions on the form of d. Primality requires d to be multiple of 3# = 6 and coprime to 7.
%H A209205 Sameen Ahmed Khan, <a href="/A209205/b209205.txt">Table of n, a(n) for n = 1..10000</a>
%H A209205 Sameen Ahmed Khan, <a href="http://arxiv.org/abs/1203.2083/">Primes in Geometric-Arithmetic Progression</a>, arXiv:1203.2083v1 [math.NT], (Mar 09 2012).
%e A209205 d = 1494 then {7*7^j + j*d}, j = 0 to 5, is {7, 1543, 3331, 6883, 22783, 125119}, which is 6 primes in geometric-arithmetic progression.
%t A209205 p = 7; gapset6d = {}; Do[If[PrimeQ[{p, p*p + d, p*p^2 + 2*d, p*p^3 + 3*d, p*p^4 + 4*d, p*p^5 + 5*d}] == {True, True, True, True, True, True}, AppendTo[gapset6d, d]], {d, 0, 100000, 2}]; gapset6d
%Y A209205 Cf. A172367, A209202, A209203, A209204, A209206, A209207, A209208, A209209, A209210.
%K A209205 nonn
%O A209205 1,1
%A A209205 _Sameen Ahmed Khan_, Mar 06 2012