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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A075350 1-1, 2*3-(2+3), 4*5*6-(4+5+6), 7*8*9*10-(7+8+9+10), ... 2
 0, 1, 105, 5006, 360295, 39069969, 5967561425, 1220096908540, 321570878428431, 106137499051583495, 42873948150095461729, 20803502274492921983130, 11938961126118491232766895, 7998487694738166709923838621 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS Harvey P. Dale, Table of n, a(n) for n = 1..226 FORMULA From Emeric Deutsch, Aug 04 2005: (Start) a(n) = product[j, j=n(n-1)/2+1..n(n+1)/2] - sum[j, j=n(n-1)/2+1..n(n+1)/2]. a(n) = [n(n+1)/2]!/[n(n-1)/2]! - n(n^2+1)/2. (End) EXAMPLE a(3) = 4*5*6-(4+5+6) = 120-15 = 105. MAPLE a:=n->(n*(n+1)/2)!/(n*(n-1)/2)!-n*(n^2+1)/2: seq(a(n), n=1..16); # Emeric Deutsch, Aug 04 2005 MATHEMATICA Times@@#-Total[#]&/@With[{nn=15}, TakeList[Range[(nn(nn+1))/2], Range[ nn]]] (* Harvey P. Dale, May 06 2019 *) CROSSREFS Cf. A075351. Sequence in context: A006361 A221791 A210138 * A165055 A168306 A075914 Adjacent sequences:  A075347 A075348 A075349 * A075351 A075352 A075353 KEYWORD nonn AUTHOR Amarnath Murthy, Sep 19 2002 EXTENSIONS More terms from Emeric Deutsch, Aug 04 2005 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 April 6 15:41 EDT 2020. Contains 333276 sequences. (Running on oeis4.)