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 A086534 #8 Dec 05 2013 19:56:19 %S A086534 2,17,271,1249,13121,13121,153089,1272833,28146689,193562623, %T A086534 652963841,1378557953,29096394751,316431663103,2191221587969, %U A086534 15356401156097,128200797454337,314394051346433,314394051346433,28344942091829249,201993039632138239,267803891553271807 %N A086534 Smallest prime p sandwiched between two numbers that are divisible by n-th powers. %C A086534 Conjecture: sequence is finite. %e A086534 a(3) = 271, 270 = 3^3*10 and 272 = 2^3*34. 271 is the smallest such number. %e A086534 a(4) = 1249, 1248 =2^4*78, 1250 = 5^4*2. 1250 is the smallest such number. %t A086534 PrimeExponents[n_] := Max[ Flatten[ Table[ # [[2]], {1}] & /@ FactorInteger[n]]]; NextPrim[n_] := Block[{k = n + 1}, While[ !PrimeQ[k], k++ ]; k]; a = Table[0, {15}]; p = 1; Do[p = NextPrim[p]; b = Min[ PrimeExponents[p - 1], PrimeExponents[p + 1]]; If[ a[[b]] == 0, a[[b]] = p; Print[b, " ", p]], {n, 1, 70000000}]; a %Y A086534 Cf. A086708, A086709. %K A086534 nonn %O A086534 1,1 %A A086534 _Amarnath Murthy_, Aug 17 2003 %E A086534 Edited and extended by _Robert G. Wilson v_, Aug 18 2003 %E A086534 a(5) corrected. a(13)-a(22) from _Donovan Johnson_, Sep 02 2008