login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A121565 a(n) is the numerator of Sum_{i=1..n} i!/(i^2). 1
1, 1, 3, 13, 11, 127, 427, 13789, 79939, 550339, 4360579, 115289, 4270982369, 608769618797, 7287249426797, 94552718917997, 1321723383637997, 336624987690165949, 5380569124281525949, 1736468713616949633031, 31234462813230541185031, 593101017091584665985031 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..21.

FORMULA

Numerator of Sum_{i=1..n} A000142(i)/A000290(i).

PROG

(PARI) a(n) = numerator(sum(i=1, n, i!/i^2)); \\ Michel Marcus, Mar 18 2018

CROSSREFS

Cf. A121566 (denominator).

Sequence in context: A272994 A273674 A214811 * A107733 A273076 A272825

Adjacent sequences:  A121562 A121563 A121564 * A121566 A121567 A121568

KEYWORD

easy,frac,nonn

AUTHOR

Jonathan Vos Post, Aug 07 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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified November 20 05:07 EST 2019. Contains 329323 sequences. (Running on oeis4.)