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A299399 a(n) = a(n-1)*a(n-2)*a(n-3)*a(n-4); a(0..3) = (1, 1, 2, 3). 2
1, 1, 2, 3, 6, 36, 1296, 839808, 235092492288, 9211413321697223245824, 2356948205087252000835395074931259831484416, 4286423488783965214900384842824017360544199884413056912194095171350270745233063936 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

A variant of A000336 which uses initial values (1,2,3,4).

A multiplicative variant of the tetranacci sequences A000078, A001631 and other variants.

LINKS

Seiichi Manyama, Table of n, a(n) for n = 0..14

FORMULA

a(n) = a(n-1)^2 / a(n-5) for n > 4.

a(n) = 2^A001631(n)*3^A000078(n).

PROG

(PARI) A299399(n, a=[1, 1, 2, 3, 6])={for(n=5, n, a[n%#a+1]=a[(n-1)%#a+1]^2\a[n%#a+1]); a[n%#a+1]}

CROSSREFS

Cf. A000336 (variant starting 1,2,3,4).

Cf. A000301 (order 2 variant), A000308 (order 3 variant).

Subsequence of A003586 (3-smooth numbers).

Cf. A000078, A001631 (additive variants).

Sequence in context: A178175 A129379 A000308 * A173501 A018340 A299121

Adjacent sequences:  A299396 A299397 A299398 * A299400 A299401 A299402

KEYWORD

nonn

AUTHOR

M. F. Hasler, Apr 22 2018

STATUS

approved

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Last modified February 26 11:49 EST 2020. Contains 332279 sequences. (Running on oeis4.)