A204771 a(n) = a(n-1) XOR (a(n-2)*3).

0, 1, 1, 2, 1, 7, 4, 17, 29, 46, 121, 243, 408, 833, 1929, 3658, 6353, 12815, 30844, 61009, 100133, 216534, 514233, 930107, 1686288, 3352737, 8264081, 15163506, 27077825, 53153175, 133991380, 243114769, 428343405, 854649182, 2120804377, 3870970883, 6937439304

Offset

0,4

Links

Ivan Panchenko, Table of n, a(n) for n = 0..200

Formula

a(0)=0, a(1)=1, a(n) = a(n-1) XOR (a(n-2)*3), where XOR is the bitwise exclusive-OR operator.

Prog

(Python)
prpr = 0
prev = 1
for i in range(99):
    current = (prev)^(prpr*3)
    print(prpr, end=', ')
    prpr = prev
    prev = current

Crossrefs

Cf. A101624: a(n) = a(n-1) XOR (a(n-2)*2).

Cf. A101625: a(n) = a(n-1) XOR (a(n-2)*4).

Sequence in context: A124048 A087059 A120872 * A141512 A143877 A319464

Adjacent sequences: A204768 A204769 A204770 * A204772 A204773 A204774

Keyword

nonn,base,easy

Author

Alex Ratushnyak, May 07 2012

Status

approved