login
Iterated octahedral numbers, starting at a(0) = 2.
1

%I #27 Mar 05 2023 11:29:25

%S 2,6,146,2074806,5954444157018557346,

%T 140744820294208035204656447906095566299588102457814757606

%N Iterated octahedral numbers, starting at a(0) = 2.

%C For additional terms see b-file.

%D Conway, J. H. and Guy, R. K. The Book of Numbers. New York: Springer-Verlag, p. 50, 1996.

%D Dickson, L. E. History of the Theory of Numbers, Vol. 2: Diophantine Analysis. New York: Chelsea, 1952.

%H Vincenzo Librandi, <a href="/A099185/b099185.txt">Table of n, a(n) for n = 0..7</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/OctahedralNumber.html">Octahedral Number</a>.

%F a(0) = 2, a(n+1) = oct(a(n)) = (2*a(n)^3 + a(n))/3.

%t RecurrenceTable[{a[0]==2, a[n+1]==(2 a[n]^3 + a[n])/3}, a, {n, 6}] (* _Vincenzo Librandi_, Sep 16 2018 *)

%Y Cf. A007501, A005900.

%K easy,nonn,less

%O 0,1

%A _Jonathan Vos Post_, Nov 15 2004

%E Edited by _Jianing Song_, Sep 16 2018