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 A173980 #15 Jan 30 2021 01:31:02
%S A173980 6,19,40,106,112,265,220,427,625,730,871,1252,1141,1717,2095,2332,
%T A173980 2716,2380,3445,6097,4465,4027,6187,6646,6415,7675,6796,7141,15991,
%U A173980 8701,9106,12400,12025,11251,12610,14995,14101,16117,16696,16201,21631,19006,22486,21967
%N A173980 a(n) is the smallest term m in A173978 for which A020639(2m-3) = prime(n), n > 1.
%H A173980 Amiram Eldar, <a href="/A173980/b173980.txt">Table of n, a(n) for n = 2..1000</a>
%H A173980 Vladimir Shevelev, <a href="http://arXiv.org/abs/0912.4006">Theorems on twin primes-dual case</a>, arXiv:0912.4006 [math.GM], 2009-2014.
%t A173980 m = 50; v = Table[0, {m}]; lpf[n_] := FactorInteger[n][[1, 1]]; aQ[n_] := (! PrimeQ[2 n - 3] || ! PrimeQ[2 n - 1]) && lpf[2 n - 3] < lpf[2 n - 1]; c = 0; n = 1; While[c < m - 1, If[aQ[n], s = PrimePi[lpf[2 n - 3]]; If[s > 1 && s <= m && v[[s]] == 0, v[[s]] = n; c++]]; n++]; Rest[v] (* _Amiram Eldar_, Sep 12 2019 *)
%Y A173980 Cf. A020639, A173978, A173977, A173979.
%K A173980 nonn
%O A173980 2,1
%A A173980 _Vladimir Shevelev_, Mar 04 2010
%E A173980 More terms from _Amiram Eldar_, Sep 12 2019