A224753 a(2)=2; thereafter a(n) = smallest number m such that a(n-1)+m = (a(n-1) followed by the leading digit of m).

2, 19, 172, 1549, 13942, 125479, 1129312, 10163809, 91474290, 823268618, 7409417569, 66684758127, 600162823149, 5401465408346, 48613188675118, 437518698076066, 3937668282684597, 35439014544161376, 318951130897452387, 2870560178077071485, 25835041602693643367, 232515374424242790305, 2092638369818185112747

Offset

1,1

Comments

The sequence is infinite: a(n) always exists.

For computer programs and examples see A224752.

Appears to be (1/4) * #{ k < 10^n | 2k has no digit 0 }, at least up to n = 8. Has anyone a simple explanation for this? - M. F. Hasler, Oct 10 2019

References

Eric Angelini, Postings to the Sequence Fans Mailing List, Apr 13 2013

Links

Table of n, a(n) for n=1..23.

Eric Angelini, Magic Sums

E. Angelini, Magic Sums [Cached copy, with permission]

Prog

(PARI) A224753_vec(N=30)=vector(N, n, N=if(n>1, A224752_nxt(N), 2)) \\ M. F. Hasler, Oct 10 2019

Crossrefs

Cf. A224752-A224761.

Sequence in context: A083196 A037526 A037735 * A037558 A037494 A037574

Adjacent sequences: A224750 A224751 A224752 * A224754 A224755 A224756

Keyword

nonn,base

Author

N. J. A. Sloane, Apr 21 2013

Status

approved