A174977 Natural numbers n = n(k) with property that string "2" appears k-times in concatenation Conc(1;n) := 1//2// ... //n (k, n = 1, 2, ...) or 0 if n(k) does not exist.

2, 12, 20, 21, 0, 22, 23, 24, 25, 26, 27, 28, 29, 32, 42, 52, 62, 72, 82, 92, 102, 112, 120, 121, 0, 122, 123, 124, 125, 126, 127, 128, 129, 132, 142, 152, 162, 172, 182, 192, 200, 201, 0, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 0, 212, 0, 220, 0, 221, 0, 0

Offset

1,1

Comments

If a natural n(k) is made of m > 1 digits "2" then (m-1) consecutive values of n(k) = 0, preceding this n(k)

References

K. Haase, P. Mauksch: Spass mit Mathe, Urania-Verlag Leipzig, Verlag Dausien Hanau, 2. Auflage 1985

E. I. Ignatjew, Mathematische Spielereien, Urania Verlag Leipzig/Jena/Berlin 1982

Links

Table of n, a(n) for n=1..61.

Example

1//2, n(1) = 2
1//...//21, n(4) = 21
n(5) does not exist, 1//...//22, n(6) = 22
1//...//29, n(13) = 29
1//...//227, n(72) = 227

Crossrefs

Cf. A174031, A174583.

Sequence in context: A073257 A240905 A303880 * A011532 A277964 A043497

Adjacent sequences: A174974 A174975 A174976 * A174978 A174979 A174980

Keyword

nonn,base

Author

Eva-Maria Zschorn (e-m.zschorn(AT)zaschendorf.km3.de), Apr 03 2010

Status

approved