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

Author

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

Keywords

• nonn
• base

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)

Examples

			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
		

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

Crossrefs

Cf. A174031, A174583.