This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A199569 Expansion 1/(1-x^2*cosech(x))=sum(n>=0, a(n)*x^n/n!^2. 0
 1, 1, 4, 30, 384, 7480, 207360, 7780080, 380190720, 23481311616, 1789201612800, 164904696633600, 18084647927808000, 2327418985883397120, 347368297708734382080, 59514548453599599360000, 11601363342443780505600000, 2552998389393196650531225600 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS FORMULA a(n)=n!^2*sum(m=1..n, m!*sum(i=0..n-m,(2^i*m^(n-m-i)* sum(k=0..i, (stirling2(i,k)*k!*stirling1(m+k,m))/(m+k)!))/(i!*(n-m-i)!))),n>0, a(0)=1. EXAMPLE 1/(1-x^2*csch(x)) = 1 + x + x^2 + (5*x^3)/6 + (2*x^4)/3 + (187*x^5)/360 + (2*x^6)/5 + (4631*x^7)/1512 + (221*x^8)/945 + (11983*x^9)/67200 + (214*x^10)/1575 + ... PROG a(n) := if n=0 then 1 else n!^2 * sum(m!*sum((2^i*m^(n-m-i)* sum((stirling2(i, k)*k!*stirling1(m+k, m))/(m+k)!, k, 0, i))/(i!*(n-m-i)!), i, 0, n-m), m, 1, n) CROSSREFS Sequence in context: A166892 A185523 A187736 * A168129 A193500 A163885 Adjacent sequences:  A199566 A199567 A199568 * A199570 A199571 A199572 KEYWORD nonn AUTHOR Vladimir Kruchinin, Nov 08 2011 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Puzzles | Hot | Classics
Recent Additions | More pages | Superseeker | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement .