A309080 - OEIS

A309080

Product minus sum of all previous terms in the sequence, starting with a(1) = 2 and a(2) = 5.

2, 5, 3, 20, 570, 341400, 116758458000, 13632577445813641200000, 185847167817698504752014113195034069600000000, 34539169785859790805229099212216829464451540660176789302662465332580254227520000000000000

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Table of n, a(n) for n=1..10.

FORMULA

a(n) = Product_{k=1..n-1} a(k) - Sum_{k=1..n-1} a(k) with a(1) = 2, a(2) = 5.

EXAMPLE

a(4) = a(1)*a(2)*a(3) - (a(1) + a(2) + a(3)) = 2*5*3 - (2 + 5 + 3) = 20.

MATHEMATICA

x1 = 2; x2 = 5; p = x1 * x2; s = x1 + x2; x = p - s; A309080 = {x1, x2, x}; Do[p = p * x; s = s + x; x = p - s; AppendTo[A309080, x], {n, 16}]

PROG

(Python)

a, n, p, s = [2, 5], 2, 2, 2

while n < 10:

p, s, n = p*a[len(a)-1], s+a[len(a)-1], n+1

a = a+[p-s]

for n in range(1, 11): print(a[n-1], end=', ') # A.H.M. Smeets, Aug 22 2019

CROSSREFS

Cf. A123702.

Sequence in context: A285743 A077216 A227617 * A058357 A176613 A097754

Adjacent sequences: A309077 A309078 A309079 * A309081 A309082 A309083

KEYWORD

nonn

AUTHOR

Christopher C. Capobianco, Jul 11 2019

STATUS

approved