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 A086712 #5 Feb 16 2025 08:32:50 %S A086712 0,1,2,2,3,3,3,4,3,4,6,6,5,5,7,8,5,6,6,7,6,8,6,8,8,7,8,10,10,9,8,9,14, %T A086712 8,10,11,10,12,8,11,8,12,13,12,11,11,13,13,13,13,13,11,11,14,11,13,16, %U A086712 12,16,14,15,16,17,13,16,15,12,18,27,15,19,18,17,15,16,15,13,18,17,15 %N A086712 Number of times the n-th prime power can be written as an arithmetic mean of two other prime powers. %H A086712 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PrimePower.html">Prime Power</a> %e A086712 n=7, A000961(7)=8=2^3: (3+13)/2=(A000961(3)+A000961(10))/2, (5+11)/2=(A000961(5)+A000961(9))/2 and (7+3^2)/2=(A000961(6)+A000961(8))/2: therefore a(7)=3. %Y A086712 Cf. A000961, A071681. %K A086712 nonn %O A086712 1,3 %A A086712 _Reinhard Zumkeller_, Aug 01 2003