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!)
 A088675 Eigenfunction of a sequence transformation. 0
 0, 1, -2, 8, -36, 160, -656, 2368, -7664, 29440, -184896, 1174272, -3395200, -21222400, 178961920, 1638189056, -27449296640, -28875071488, 3234263731200, -10138343231488, -422012179953664, 3426627065331712, 59293997091528704 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS G.f. A(x) satisfies x=(1+4*A(x))A(A(x)). LINKS FORMULA a(n)=T(n,1), T(n,m)=1/2*(sum(k=1..n-m, 4^k*T(n-m,k)*binomial(k+m-1,m-1)*(-1)^(k))-sum(k=m+1..n-1, T(n,k)*T(k,m))), n>m, T(n,n)=1. [Vladimir Kruchinin, May 04 2012] PROG (PARI) a(n)=local(A); if(n<1, 0, A=x; for(k=1, n, A=Pol(A+serreverse(A+x*O(x^k))/(1+4*x))/2); polcoeff(A, n)) (Maxima) T(n, m):=if n=m then 1 else 1/2*(sum(4^k*T(n-m, k)*binomial(k+m-1, m-1)*(-1)^(k), k, 1, n-m)-sum(T(n, k)*T(k, m), k, m+1, n-1)); makelist(T(n, 1), n, 1, 10); [Vladimir Kruchinin, May 04 2012] CROSSREFS Sequence in context: A123290 A321110 A228791 * A228197 A326244 A027743 Adjacent sequences:  A088672 A088673 A088674 * A088676 A088677 A088678 KEYWORD sign AUTHOR Michael Somos, Oct 04 2003 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 5 15:11 EST 2019. Contains 329753 sequences. (Running on oeis4.)