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 A015915 #26 Jul 04 2021 00:33:14 %S A015915 3,5,11,23,27,29,53,59,71,89,101,131,149,173,191,233,263,269,359,389, %T A015915 401,431,449,479,491,563,569,593,599,653,683,701,719,743,761,821,911, %U A015915 929,983,1013,1031,1061,1109,1163,1193,1223,1229,1283,1289 %N A015915 Numbers k such that sigma(k) + 8 = sigma(k+8). %C A015915 Different from A023202. Below 1000000 four composites were found [27, 1615, 1885, 218984] satisfying the "sigma(k) + 8 = sigma(k+8)" relation, together with more than 8000 primes. - _Labos Elemer_, May 23 2000 %H A015915 Vincenzo Librandi, <a href="/A015915/b015915.txt">Table of n, a(n) for n = 1..1000</a> %e A015915 sigma(27) + 8 = 48 = sigma(27+8), so 27 is in the sequence. %t A015915 Select[Range[1300],DivisorSigma[1,#]+8==DivisorSigma[1,#+8]&] (* _Harvey P. Dale_, Jul 16 2011 *) %o A015915 (PARI) is(n)=sigma(n)+8==sigma(n+8) \\ _Charles R Greathouse IV_, Mar 11 2014 %Y A015915 Cf. A000203, A015913-A015917, A023200-A023203, A046133, A001359, A054799. %Y A015915 Composite solutions are in A059118. %K A015915 nonn %O A015915 1,1 %A A015915 _Robert G. Wilson v_