cp's OEIS Frontend

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.

A036432 Sets a record for the number of positive integers which, when added to the number of their divisors, gives n.

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%I A036432 #21 Feb 24 2020 06:11:53
%S A036432 1,2,7,38,122,2766,64686,1972296,5387768,56208248,753815160,
%T A036432 130065181784,5398921735160
%N A036432 Sets a record for the number of positive integers which, when added to the number of their divisors, gives n.
%C A036432 Invented by the HR concept formation program.
%C A036432 a(13) > 10^13. - _Giovanni Resta_, Feb 24 2020
%H A036432 S. Colton, <a href="http://www.cs.uwaterloo.ca/journals/JIS/colton/joisol.html">Refactorable Numbers - A Machine Invention</a>, J. Integer Sequences, Vol. 2, 1999, #2.
%H A036432 S. Colton, <a href="http://web.archive.org/web/20070831060523/http://www.dai.ed.ac.uk/homes/simonco/research/hr/">HR - Automatic Theory Formation in Pure Mathematics</a>
%F A036432 Sets record for |{b in N : b + tau(b) = n}|.
%e A036432 1 [ first with 0 ].
%e A036432 2=1+tau(1) [ first with 1 ].
%e A036432 7=4+tau(4) and 5+tau(5) [ first with 2 ].
%e A036432 38=30+tau(30) and 32+tau(32) and 34+tau(34) [ first with 3 ].
%o A036432 (PARI) nbi(n) = {nb = 0; for (i = 1, n, if ((i + numdiv(i)) == n, nb++);); nb;}
%o A036432 lista(nn) = {rec = -1; for (n = 1, nn, new = nbi(n); if (new > rec, print1(n, ", "); rec = new;););} \\ _Michel Marcus_, Aug 31 2013
%Y A036432 Cf. A036431.
%K A036432 hard,nonn,nice,more
%O A036432 0,2
%A A036432 Simon Colton (simonco(AT)cs.york.ac.uk)
%E A036432 More terms from Julian Richardson (julianr(AT)dai.ed.ac.uk), who has searched up to 100000000.
%E A036432 a(10)-a(11) from _Donovan Johnson_, Feb 19 2009
%E A036432 a(12) from _Giovanni Resta_, Feb 24 2020