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!)
 A130709 Number of compositions of n such that the largest part is coprime to every other part. 1
 1, 1, 2, 4, 7, 13, 22, 41, 75, 138, 255, 482, 911, 1735, 3316, 6370, 12306, 23907, 46666, 91500, 180119, 355820, 705061, 1400722, 2788718, 5561720, 11107305, 22205839, 44429088, 88942741, 178120533, 356787834, 714732794, 1431763102, 2867860060 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS FORMULA G.f.: 1/(1-x) + Sum_{n>1} x^n/(1-Sum_{d | 1<=d<=n, gcd(n,d)=1} x^d)^2. MAPLE A130709 := proc(n) local gf, den, i, d ; gf := 0 ; for i from 2 to n do den := 1 ; for d from 1 to i-1 do if gcd(d, i) = 1 then den := den-x^d ; fi ; od ; gf := taylor(gf+x^i/den^2, x=0, n+1) ; od: 1+coeftayl(gf, x=0, n) ; end: seq(A130709(n), n=0..40) ; # R. J. Mathar, Oct 28 2007 CROSSREFS Sequence in context: A254007 A001036 A054150 * A051013 A128609 A168043 Adjacent sequences:  A130706 A130707 A130708 * A130710 A130711 A130712 KEYWORD easy,nonn AUTHOR Vladeta Jovovic, Jul 01 2007 EXTENSIONS More terms from R. J. Mathar, Oct 28 2007 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 10 21:53 EST 2019. Contains 329909 sequences. (Running on oeis4.)