login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A036432 Sets a record for the number of positive integers which, when added to the number of their divisors, gives n. 1
1, 2, 7, 38, 122, 2766, 64686, 1972296, 5387768, 56208248, 753815160, 130065181784 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Invented by the HR concept formation program.

LINKS

Table of n, a(n) for n=0..11.

S. Colton, Refactorable Numbers - A Machine Invention, J. Integer Sequences, Vol. 2, 1999, #2.

S. Colton, HR - Automatic Theory Formation in Pure Mathematics

FORMULA

Sets record for |{b in N : b + tau(b) = n}|.

EXAMPLE

1 [ first with 0 ].

2=1+tau(1) [ first with 1 ].

7=4+tau(4) and 5+tau(5) [ first with 2 ].

38=30+tau(30) and 32+tau(32) and 34+tau(34) [ first with 3 ].

PROG

(PARI) nbi(n) = {nb = 0; for (i = 1, n, if ((i + numdiv(i)) == n, nb++); ); nb; }

lista(nn) = {rec = -1; for (n = 1, nn, new = nbi(n); if (new > rec, print1(n, ", "); rec = new; ); ); } \\ Michel Marcus, Aug 31 2013

CROSSREFS

Cf. A036431.

Sequence in context: A182331 A173762 A180269 * A275621 A094431 A256032

Adjacent sequences:  A036429 A036430 A036431 * A036433 A036434 A036435

KEYWORD

hard,nonn,nice,more

AUTHOR

Simon Colton (simonco(AT)cs.york.ac.uk)

EXTENSIONS

More terms from Julian Richardson (julianr(AT)dai.ed.ac.uk), who has searched up to 100000000.

a(10)-a(11) from Donovan Johnson, Feb 19 2009

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 21 18:43 EDT 2019. Contains 323444 sequences. (Running on oeis4.)