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 A286837 #15 Aug 04 2019 04:50:49 %S A286837 1386,6790,8130,18618,21378,27654,38874,60030,64020,71058,89178,92130, %T A286837 97014,117114,118902,180438,182226,224058,247044,396078,495114,510906, %U A286837 528510,723486,855966,979098,1007562,1012380,1032360,1141194,1302906,1410294 %N A286837 Numbers n such that usigma(n) = usigma(2*n+1) where usigma(n) = A034448(n). %C A286837 46495995 = 3*5*7*13*23*1481 is the smallest odd term of this sequence. %H A286837 Amiram Eldar, <a href="/A286837/b286837.txt">Table of n, a(n) for n = 1..1000</a> %t A286837 usigma[1] = 1; usigma[n_] := Times @@ (1 + Power @@@ FactorInteger[n]); Select[Range[10^5], usigma[#] == usigma[2#+1] &] (* _Amiram Eldar_, Aug 04 2019 *) %o A286837 (PARI) a034448(n) = sumdivmult(n, d, if(gcd(d, n/d)==1, d)); %o A286837 isok(n) = a034448(n)==a034448(2*n+1); \\ after _Charles R Greathouse IV_ at A034448 %Y A286837 Cf. A034448, A064125, A272553. %K A286837 nonn %O A286837 1,1 %A A286837 _Altug Alkan_, Aug 01 2017