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 A107607 #12 Jun 13 2017 01:37:46 %S A107607 1,2,12,15,38,39,100,118,152,190,212,258,352,462,542,690,741,746,1285, %T A107607 1396,1417,1632,2119,2243,2318,2603,3370,3777,4073,4155,4485,4522, %U A107607 4600,4719,5317,5446,6697,6748,6985,7144,7520,7595,9492,9551,12010,12985 %N A107607 Numbers n such that prime(n) - n is a perfect power. %e A107607 Prime(12) - 12 = 37 - 12 = 25 = 5^2. %t A107607 f[n_] := Prime[n] - n; Select[Range[10^4], ! GCD @@ Last /@ FactorInteger[f[ # ]] == 1 &] (* _Ray Chandler_, May 21 2005 *) %o A107607 (PARI) isA107607(n)=(ispower(prime(n)-n) > 1) || (prime(n)-n == 1) \\ _Michael B. Porter_, Sep 28 2009 %Y A107607 Cf. A001597 (perfect powers), A107605, A107606, A107608 (associated prime(n)-n). %K A107607 nonn %O A107607 1,2 %A A107607 _Zak Seidov_, May 17 2005 %E A107607 Extended by _Ray Chandler_, May 21 2005