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 A115920 #27 Jul 22 2021 07:59:41 %S A115920 1,69,258,270,276,609,639,2391,2556,2931,3409,3678,3679,4291,5092, %T A115920 6937,8251,10231,12087,12931,15480,16387,20850,22644,22893,24369, %U A115920 26145,26442,27846,28764,29880,29958,30823,31812,32658,34207,34758 %N A115920 Numbers k such that the digits of sigma(k) are a permutation of those of k, in base 10. %C A115920 There is some m > 1 such that a(n) > m*n for all n > 1. This follows from the positive density of numbers k such that sigma(k)/k > 10. - _Charles R Greathouse IV_, Sep 07 2012 %H A115920 V. Raman, <a href="/A115920/b115920.txt">Table of n, a(n) for n = 1..10000</a> %e A115920 sigma(10231) = 11032, sigma(31812) = 81312. %t A115920 Select[Range[35000],Sort[IntegerDigits[#]]==Sort[ IntegerDigits[ DivisorSigma[ 1,#]]]&] (* _Harvey P. Dale_, May 09 2013 *) %o A115920 (Python) %o A115920 from sympy import divisor_sigma %o A115920 A115920_list = [n for n in range(1,10**4) if sorted(str(divisor_sigma(n))) == sorted(str(n))] # _Chai Wah Wu_, Dec 13 2015 %o A115920 (PARI) isok(n) = vecsort(digits(n)) == vecsort(digits(sigma(n))); \\ _Michel Marcus_, Dec 13 2015 and May 27 2018 %Y A115920 Cf. A000203, A114065, A115921, A175795. %K A115920 nonn,base %O A115920 1,2 %A A115920 _Giovanni Resta_, Feb 06 2006