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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A245283 a(n) = a(n-1) * (a(n-1) + a(n-2)) / a(n-4) with a(1) = a(2) = a(3) = a(4) = 1. 2
1, 1, 1, 1, 2, 6, 48, 2592, 3421440, 1952520007680, 79423772100432548659200, 2433694280407609647520301298079459442688000, 1731103819002733625504286414686785477293241305893841298989509923950758461440000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..17

FORMULA

a(n+3) = a(n+2) * A245384(n) for n>0.

MATHEMATICA

a[ n_] := If[ n<5, 1, a[n] = a[n-1] (a[n-1] + a[n-2]) / a[n-4]];

RecurrenceTable[{a[n] == a[n-1]*(a[n-1] + a[n-2])/a[n-4], a[1] == a[2] == a[3] == a[4] == 1}, a, {n, 1, 10}] (* G. C. Greubel, Aug 06 2018 *)

PROG

(PARI) {a(n) = if( n<5, 1, a(n-1) * (a(n-1) + a(n-2)) / a(n-4))};

(MAGMA) I:=[1, 1, 1, 1]; [n le 4 select I[n] else Self(n-1)*(Self(n-1) + Self(n-2))/Self(n-4): n in [1..10]]; // G. C. Greubel, Aug 06 2018

CROSSREFS

Cf. A245384.

Sequence in context: A141609 A096313 A230053 * A126023 A088679 A161766

Adjacent sequences:  A245280 A245281 A245282 * A245284 A245285 A245286

KEYWORD

nonn

AUTHOR

Michael Somos, Aug 21 2014

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 February 24 17:00 EST 2020. Contains 332209 sequences. (Running on oeis4.)