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 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 *) nxt[{a_, b_, c_, d_}]:={b, c, d, d (d+c)/a}; NestList[nxt, {1, 1, 1, 1}, 15][[All, 1]] (* Harvey P. Dale, Jun 25 2021 *) 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: A096313 A346788 A230053 * A126023 A088679 A161766 Adjacent sequences:  A245280 A245281 A245282 * A245284 A245285 A245286 KEYWORD nonn AUTHOR Michael Somos, Aug 21 2014 STATUS approved

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Last modified January 23 10:11 EST 2022. Contains 350510 sequences. (Running on oeis4.)