A062000 - OEIS (original) (raw)

A062000

a(n) = a(n-1)^2 - a(n-2)^2 with a(0) = 0, a(1) = 2.

2

0, 2, 4, 12, 128, 16240, 263721216, 69548879504781056, 4837046640370554355727482727956480, 23397020201120067002755280700388456275000098577861376610994277515264

FORMULA

a(n) ~ c^(2^n), where c = 1.35388068260888709216374860554901303232201699191445590979673901150215855854... . - Vaclav Kotesovec, Dec 17 2014

MATHEMATICA

RecurrenceTable[{a[0]==0, a[1]==2, a[n]==a[n-1]^2 - a[n-2]^2}, a, {n, 0, 10}] (* Vaclav Kotesovec, Dec 17 2014 *)

PROG

(PARI) { for (n=0, 12, if (n>1, a=a1^2 - a2^2; a2=a1; a1=a, if (n==0, a=a2=0, a=a1=2)); write("b062000.txt", n, " ", a) ) } \\ Harry J. Smith, Jul 29 2009

(SageMath)

if (n<2): return 2*n

else: return a(n-1)^2 - a(n-2)^2