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 A261716 #34 Aug 25 2016 21:42:27
%S A261716 3,27,115,643
%N A261716 Odd numbers that result in a prime when their cubes are concatenated with the cubes of all smaller odd numbers in descending order.
%H A261716 G. L. Honaker, Jr. and C. Caldwell, <a href="https://primes.utm.edu/curios/page.php?number_id=9959">19683...25271 (51-digits)</a>
%e A261716 A000578(3) = 27. The only odd number less than 3 is 1 with A000578(1) = 1. Concatenating the two resulting cubes in descending order one gets 271 which is prime, so 3 is a term of the sequence.
%t A261716 fQ[n_] := PrimeQ[ FromDigits[ Flatten[ IntegerDigits[ Range[2n - 1, 1, -2]^3]]]]; k = 1; lst = {}; While[k < 1501, If[ fQ[k], AppendTo[lst, 2k - 1]; Print[2k - 1]]; k++]; lst (* _Robert G. Wilson v_, Sep 16 2015 *)
%o A261716 (PARI) odd(n) = 2*n-1
%o A261716 con(n) = s=""; k=n; while(k > 0, s=Str(s, Str(odd(k)^3)); k--); eval(s)
%o A261716 isok(n) = ispseudoprime(con(n))
%o A261716 terms(n) = i=0; x=1; while(i < n, if(isok(x), print1(odd(x), ", "); i++); x++)
%o A261716 terms(4) \\ print initial four terms
%Y A261716 Cf. A091314, A089922.
%K A261716 nonn,base,more
%O A261716 1,1
%A A261716 _Felix Fröhlich_, Aug 29 2015
%E A261716 First 4 terms confirmed by _Robert G. Wilson v_, Sep 16 2015 and no more < 3000.