This site is supported by donations to The OEIS Foundation.

 Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing. Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A304288 Denominators a(n) of the fractions Sum_{n>=1} {n/a(n)} = 1/a(1) + 2/a(2) + 3/a(3) + ... such that the sum has the concatenation of these denominators as decimal part. Case a(1) = 3. 26
 3, 64, 9122, 247449223, 351840295262110531, 628514983855026936648291640964480216 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS It appears that fractions of this kind exist only for a(1) equal to 3 (this sequence), 10 (A304289), 11 (A305661), 14 (A305662), and 31 (A305663). a(7) has 73 digits. - Giovanni Resta, Jun 08 2018 LINKS EXAMPLE 1/3 = 0.333... 1/3 + 2/64 = 0.364583... 1/3 + 2/64 + 3/9122 = 0.3649122085... The sum is 0.3 64 9122 ... MAPLE P:=proc(q, h) local a, b, d, n, t; a:=1/h; b:=ilog10(h)+1; d:=h; print(d); t:=2; for n from 1 to q do if trunc(evalf(a+t/n, 100)*10^(b+ilog10(n)+1))=d*10^(ilog10(n)+1)+n then b:=b+ilog10(n)+1; d:=d*10^(ilog10(n)+1)+n; a:=a+t/n; t:=t+1; print(n);  fi; od; end: P(10^20, 3); CROSSREFS Cf. A302932, A302933, A303388, A304285, A304286, A304287, A304289, A305661, A305662, A305663, A305664, A305665, A305666. Sequence in context: A231823 A174841 A084883 * A275044 A205645 A326429 Adjacent sequences:  A304285 A304286 A304287 * A304289 A304290 A304291 KEYWORD nonn,base AUTHOR Paolo P. Lava, Jun 08 2018 EXTENSIONS a(4)-a(6) from Giovanni Resta, Jun 08 2018 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 09:33 EST 2019. Contains 329843 sequences. (Running on oeis4.)