A045646 Alternative version of A006050.

1, 10, 19, 199, 19999999999999999999999

Offset

0,2

Comments

This is also the smallest n such that digit sum of n = previous term. - Dominick Cancilla, Aug 09 2010

References

H. J. Hindin, The additive persistence of a number, J. Rec. Math., 7 (No. 2, 1974), 134-135.

Links

Table of n, a(n) for n=0..4.

N. J. A. Sloane, The persistence of a number, J. Recreational Math., 6 (1973), 97-98.

Formula

For n > 1, a(n) = 2*10^((a(n-1)-1)/9) - 1.

Mathematica

Join[{1}, NestList[2*10^((#-1)/9)-1&, 10, 3]] (* Harvey P. Dale, Sep 20 2011 *)

Crossrefs

Cf. A003001, A006050.

Sequence in context: A121725 A110368 A006050 * A334137 A212594 A255529

Adjacent sequences: A045643 A045644 A045645 * A045647 A045648 A045649

Keyword

nonn,base,nice

Author

N. J. A. Sloane

Extensions

Next term is 1 followed by 2222222222222222222222 9s.

Status

approved