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 A083794 #18 Jul 03 2025 10:54:43 %S A083794 1,2,4,5,6,7,8,9,10,11,12,13,14,16,17,18,19,20,21,23,24,25,26,28,29, %T A083794 30,31,32,33,36,37,38,40,41,42,43,44,46,47,48,49,50,51,52,53,54,55,56, %U A083794 57,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,77,78,79,80,81,82 %N A083794 Numbers k such that tau(k) is different from tau(k-1), where tau(m) = number of divisors of m. %H A083794 Michael De Vlieger, <a href="/A083794/b083794.txt">Table of n, a(n) for n = 1..10000</a> %H A083794 P. Erdős, <a href="http://www.renyi.hu/~p_erdos/1936-03.pdf">On a problem of Chowla and some related problems</a>, Proc. Cambridge Philos. Soc. 32 (1936), pp. 530-540. %F A083794 Erdős proved that a(n) ~ n. - _Charles R Greathouse IV_, Dec 05 2012 %p A083794 with(numtheory): for n from 1 to 150 do if tau(n) <> tau(n-1) then printf(`%d,`,n) fi: od: # _James Sellers_, May 19 2003 %t A083794 a083794[n_] := %t A083794 Prepend[Select[Range[1, n], %t A083794 DivisorSigma[0, #] != DivisorSigma[0, # - 1] &], 1]; a083794[82] (* _Michael De Vlieger_, Dec 24 2014 *) %o A083794 (PARI) is(n)=numdiv(n-1)!=numdiv(n) %Y A083794 Cf. A083795. %K A083794 nonn %O A083794 1,2 %A A083794 _Amarnath Murthy_, May 07 2003 %E A083794 More terms from _James Sellers_, May 19 2003