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 A276713 #13 Nov 12 2022 13:12:02 %S A276713 2,35,55,62,74,82,91,102,115,119,122,135,142,143,155,158,172,186,202, %T A276713 203,206,214,215,218,242,255,259,262,282,295,298,299,302,323,326,343, %U A276713 351,354,355,362,391,395,399,425,426,435,451,466,478,482,492,502,511,514 %N A276713 Numbers n such that n and n+3 have the same number of divisors (A000005). %H A276713 Jaroslav Krizek, <a href="/A276713/b276713.txt">Table of n, a(n) for n = 1..1000</a> %e A276713 35 is in sequence because tau(35) = tau(38) = 4. %p A276713 with(numtheory): A276713:=n->`if`(tau(n) = tau(n+3), n, NULL): seq(A276713(n), n=1..10^3); # _Wesley Ivan Hurt_, May 02 2017 %t A276713 SequencePosition[DivisorSigma[0,Range[600]],{x_,_,_,x_}][[All,1]] (* _Harvey P. Dale_, Nov 12 2022 *) %o A276713 (Magma) [n: n in [1..10000] | NumberOfDivisors(n) eq NumberOfDivisors(n+3)] %o A276713 (PARI) isok(n) = numdiv(n) == numdiv(n+3); \\ _Michel Marcus_, May 03 2017 %Y A276713 Cf. A065559 (smallest k such that tau(k) = tau(k+n)), A015861 (sigma(n) = sigma(n+3)), A276714. %Y A276713 Cf. Similar sequences with numbers n such that n and n+k have the same number of divisors for k = 1: A005237, for k = 2: A062832. %K A276713 nonn %O A276713 1,1 %A A276713 _Jaroslav Krizek_, Sep 16 2016