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 A284743 #23 Aug 18 2017 14:31:49
%S A284743 2,3,6,7,11,15,19,23
%N A284743 Positive numbers that are not the sum of (any number of) distinct perfect powers (A001597).
%C A284743 Subsequence of A001422.
%C A284743 David Wells noted that 23 is the largest integer that is not the sum of distinct powers.
%D A284743 David Wells, The Penguin Dictionary of Curious and Interesting Numbers, Penguin 1987, p. 101.
%e A284743 22 is not in the sequence since 22 = 1 + 2^2 + 2^3 + 3^2.
%t A284743 PerfectPowerQ[n_] := n==1 || GCD@@FactorInteger[n][[All, 2]]>1; a=Select[Range[128], PerfectPowerQ[#] &]; nn = Dimensions[a][[1]]; t=Rest[CoefficientList[Series[Product[(1 + x^a[[k]]),{k,nn}],{x,0,a[[nn]]}], x]]; Flatten[Position[t, 0]]
%Y A284743 Cf. A001422, A001597.
%K A284743 nonn,fini,full
%O A284743 1,1
%A A284743 _Amiram Eldar_, Apr 01 2017