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A061322 a(n) = a(n-1) * (1 + a(n-1)/n^2) with a(0) = 2. 1
2, 6, 15, 40, 140, 924, 24640, 12415040, 2408343949440, 71606426901226335015040, 51274803735606705472274088614112357905277056, 21728144612603201307908899563300049012978385050783094682272184269369267136230071558272 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,1
COMMENTS
Only first 42 terms are integers (see A003504).
LINKS
FORMULA
a(n) = a(n-1) + A003504(n+1)^2, a(n-1) = n * A003504(n+1). a(n) = A061314(2, n).
EXAMPLE
a(2) = 6 * (1 + 6/2^2) = 15.
PROG
(PARI) {a(n) = local(x); if( n<1, 2 * (n==0), (x = a(n-1)) + (x/n)^2)} /* Michael Somos, Apr 02 2006 */
CROSSREFS
Sequence in context: A206000 A316981 A319560 * A004664 A074446 A303551
KEYWORD
nonn
AUTHOR
Henry Bottomley, Apr 24 2001
STATUS
approved

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Last modified March 19 03:21 EDT 2024. Contains 370952 sequences. (Running on oeis4.)