A003620 Number of iterations until 3n reaches 153 under x goes to sum of cubes of digits map.

3, 10, 4, 5, 10, 2, 5, 3, 2, 3, 6, 6, 6, 3, 5, 6, 10, 5, 5, 10, 6, 6, 6, 2, 5, 8, 2, 6, 8, 4, 6, 6, 4, 5, 10, 2, 4, 7, 11, 5, 7, 9, 10, 7, 1, 6, 7, 11, 7, 10, 0, 6, 8, 9, 6, 4, 11, 7, 13, 2, 6, 4, 4, 10, 8, 4, 5, 3, 2, 5, 7, 9, 10, 4, 8, 8, 7, 5, 10, 3

Offset: 1

Author

N. J. A. Sloane, Mira Bernstein

Keywords

• nonn
• base

Comments

a(n) = A165331(A008585(n)). [From Reinhard Zumkeller, Nov 21 2009]

References

• J. Roberts, Lure of the Integers, Math. Assoc. America, 1992, p. 13.
• N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Cf. A055012. [From Reinhard Zumkeller, Nov 21 2009]

Programs

Mathematica

Table[Length[NestWhileList[Total[IntegerDigits[#]^3]&,3n,#!=153&]]-1,{n,80}] (* Harvey P. Dale, Dec 19 2011 *)