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!)
 A114347 Cumulative sum of triple factorial numbers a(n) = n!!! (A007661). 6
 1, 2, 4, 7, 11, 21, 39, 67, 147, 309, 589, 1469, 3413, 7053, 19373, 48533, 106773, 316213, 841093, 1947653, 6136453, 17158933, 41503253, 137845653, 402385173, 1010993173, 3515895573, 10658462613, 27699486613, 100341656213 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Triple factorial numbers n!!! = n*(n-3)!!!, 0!!! = 1!!! = 1, 2!!! = 2. The cumulative sum a(n) is prime for n = 1, 3, 4, 7, 12, 14, 15, 17, 19. The cumulative sum a(n) is semiprime for n = 2, 5, 6, 9, 10, 11, 13, 16, 18, 20, 22, 26, 28, 29. REFERENCES J. Spanier and K. B. Oldham, An Atlas of Functions, Hemisphere, NY, 1987, p. 23. LINKS FORMULA a(n) = Sum_{i=0..n} i!!!. a(n) = Sum_{i=0..n} A007661(i). EXAMPLE a(29) = 1 + 1 + 2 + 3 + 4 + 10 + 18 + 28 + 80 + 162 + 280 + 880 + 1944 + 3640 + 12320 + 29160 + 58240 + 209440 + 524880 + 1106560 + 4188800 + 11022480 + 24344320 + 96342400 + 264539520 + 608608000 + 2504902400 + 7142567040 + 17041024000 + 726421696 = 100341656213 = 79 * 1270147547. CROSSREFS Cf. A000040, A001358, A007661. Sequence in context: A304916 A024927 A018077 * A293684 A332274 A071250 Adjacent sequences:  A114344 A114345 A114346 * A114348 A114349 A114350 KEYWORD easy,nonn AUTHOR Jonathan Vos Post, Feb 08 2006 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 September 20 02:19 EDT 2021. Contains 347577 sequences. (Running on oeis4.)