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A099185 Iterated octahedral numbers, starting at a(0) = 2. 1
2, 6, 146, 2074806, 5954444157018557346, 140744820294208035204656447906095566299588102457814757606, 1858685896365056640452604182778243755878210128325493631436394942328487801924642707284183892998994140529418479176238949509991689659112331788418314832322689820822344586546 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

REFERENCES

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

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

J. V. Post, "Iterated Triangular numbers", preprint.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..7

Eric Weisstein's World of Mathematics, "Octahedral Number."

FORMULA

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

MATHEMATICA

RecurrenceTable[{a[0]==2, a[n+1]==(2 a[n]^3 + a[n])/3}, a, {n, 6}] (* Vincenzo Librandi, Sep 16 2018 *)

CROSSREFS

Cf. A007501, A005900.

Sequence in context: A333444 A274986 A024397 * A015173 A122570 A088430

Adjacent sequences:  A099182 A099183 A099184 * A099186 A099187 A099188

KEYWORD

easy,nonn,less

AUTHOR

Jonathan Vos Post, Nov 15 2004

EXTENSIONS

Edited by Jianing Song, Sep 16 2018

STATUS

approved

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Last modified April 19 03:42 EDT 2021. Contains 343105 sequences. (Running on oeis4.)