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 A247137 #18 Dec 10 2016 19:36:43 %S A247137 119,161,343,369,527,711,721,833,959,1081,1127,1241,1695,1767,2047, %T A247137 3281,3335,3553,3713,4207,4633,4681,5047,5215,6713,6887,7327,7775, %U A247137 9641,12319,14031,16617,16999,18473,19199,22145,27009,27913,29449,31679,32239,32599,37241,44801,45385,47865,47959,50279,52319,56033 %N A247137 Numbers for which the root mean square of nontrivial divisors is an integer and which are not a square of prime numbers. %C A247137 That's the numbers which are in A247136 and not in A001248. %H A247137 Daniel Lignon and Charles R Greathouse IV, <a href="/A247137/b247137.txt">Table of n, a(n) for n = 1..10000</a> (terms up to 148 from Lignon) %o A247137 (PARI) integralRMS(v)=my(t=norml2(v)/#v); denominator(t)==1 && issquare(t) %o A247137 is(n)=my(d=divisors(n)); #d>3 && integralRMS(d[2..#d-1]) \\ _Charles R Greathouse IV_, Nov 20 2014 %Y A247137 Cf. A247136 (Numbers for which the root mean square of nontrivial divisors is an integer). %K A247137 nonn %O A247137 1,1 %A A247137 _Daniel Lignon_, Nov 20 2014