The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A212607 Number of distinct sums <= 1 of distinct reciprocals of integers <= n. 3
 1, 2, 3, 5, 8, 14, 21, 38, 70, 129, 238, 440, 504, 949, 1790, 2301, 4363, 8272, 12408, 23604, 26675, 45724, 87781, 168549, 181989, 351076, 677339, 1306894, 1399054, 2709128, 2795144, 5423805, 10525050 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS EXAMPLE a(3) = 5 counts numbers { 0, 1/3, 1/2, 5/6, 1 }, each of which is can be represented as the sum of distinct reciprocals 1/1, 1/2, and 1/3. MAPLE s:= proc(n) option remember;       `if`(n=0, {0}, map(x-> `if`(n-1 nops(s(n)): seq(a(n), n=0..20);  # Alois P. Heinz, May 23 2012 MATHEMATICA s[_] := s[n] = If[n == 0, {0}, If[n-1 < n*#, #, {#, # + 1/n}]& /@ s[n-1] // Flatten]; a[n_] := Length[s[n]]; Table[Print[n, " ", a[n]]; a[n], {n, 0, 32}] (* Jean-François Alcover, May 13 2019, after Alois P. Heinz *) CROSSREFS For possibly non-distinct reciprocals, see A212606. Cf. A020473, A092669, A092671, A208480. Sequence in context: A034413 A034416 A306912 * A056366 A000046 A293641 Adjacent sequences:  A212604 A212605 A212606 * A212608 A212609 A212610 KEYWORD nonn AUTHOR Max Alekseyev, May 22 2012 EXTENSIONS a(27)-a(32) from Alois P. Heinz, May 23 2012 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.

Last modified December 7 12:17 EST 2021. Contains 349581 sequences. (Running on oeis4.)