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A218150 5^((6+5*n+n^3)/6). 2
1, 5, 25, 625, 390625, 30517578125, 1490116119384765625, 227373675443232059478759765625, 542101086242752217003726400434970855712890625, 100974195868289511092701256356196637398170423693954944610595703125 (list; graph; refs; listen; history; text; internal format)
OFFSET

-1,2

COMMENTS

a(n) = a(0) * product(i=1,2,...k) r(i)^C(n,i), C(n,i)=0 for all i > n.

Here, it is submitted a special case of the geometric-geometric sequence having finite ratios, that is, k consecutive rows of ratios, whose first terms are r(1), r(2), r(3),..., r(k), the last row (k-th row) being of a constant ratio, with k=3, a(0) = r(1) = r(2) = r(3) = 5.

LINKS

Table of n, a(n) for n=-1..8.

FORMULA

a(n) = a(n-1)*(2^(1+n*(n-1)/2)), with a(0)=5.

EXAMPLE

a(3) = 5^((6+5*3+3^3)/6) = 5^((6+15+27)/6) = 5^(48/6) = 5^8 = 390625.

PROG

(Maxima) A218150(n):=5^((6+5*n+n^3)/6)$

makelist(A218150(n), n, -1, 9); /* Martin Ettl, Oct 31 2012 */

(PARI) a(n)=5^(n*(n^2+5)/6+1) \\ Charles R Greathouse IV, Jan 06 2013

CROSSREFS

Sequence in context: A030995 A067270 A215118 * A176594 A274463 A279835

Adjacent sequences:  A218147 A218148 A218149 * A218151 A218152 A218153

KEYWORD

nonn,easy

AUTHOR

Mokhtar Mohamed, Oct 22 2012

STATUS

approved

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Last modified October 21 19:16 EDT 2021. Contains 348155 sequences. (Running on oeis4.)