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 A158287 #19 Feb 04 2025 07:18:51 %S A158287 287,1673,3055,6665,9545,9799,9855,21385,26095,34697,46655,66815, %T A158287 68593,68985,125255,155287,182665,242879,273265,380511,391345,404055, %U A158287 421655,627215,730145,814463,823537,876785,1069895,1087009,1166399,1204281,1256489,1289441 %N A158287 Composite RMS numbers: composite numbers c such that root mean square of divisors of c is an integer. %C A158287 a(n) = composite number c (A002808), iff sqrt(sigma_2(c)/tau(c)) = sqrt(A001157(c)/A000005(c)) = k, for k = natural numbers (A000027). Prime RMS numbers (NSW primes) in A088165. %C A158287 16 of the first 1654 terms are even (the smallest is 2217231104). The first 16 even terms are all divisible by 30976. - _Donovan Johnson_, Apr 17 2013 %H A158287 Giovanni Resta, <a href="/A158287/b158287.txt">Table of n, a(n) for n = 1..7424</a> (terms < 10^13, first 1654 terms from Donovan Johnson) %e A158287 a(1) = 287, sqrt(A001157(287)/A000005(287)) = sqrt(84100/4) = 145, number 145 is an integer. %t A158287 Select[Range[13*10^5],CompositeQ[#]&&IntegerQ[RootMeanSquare[Divisors[ #]]]&] (* _Harvey P. Dale_, Sep 23 2022 *) %Y A158287 Cf. A001157, A000005, A088165, A140480. %K A158287 nonn %O A158287 1,1 %A A158287 _Jaroslav Krizek_, Mar 15 2009