A105391 Numbers m such that there are an equal number of numbers <= m that are contained and that are not contained in the concatenation of terms <= m in A048991.

740, 1260, 1262, 5230, 15804, 15814, 15816, 36294, 194876, 213868

Offset

1,1

Comments

A105390(a(n)) = a(n)/2.

There are no other terms <= 600000. The plots in a105390.gif strongly suggest that the sequence is complete. - Klaus Brockhaus, Aug 15 2007

Links

Table of n, a(n) for n=1..10.

Nick Hobson, Python program for this sequence

Example

A105390(n) < n/2 for n < a(1)=740;
A105390(n) > n/2 for n with 740 < n < a(2)=1260;
A105390(1261)=631, A105390(a(3))=A105390(1262)=631;
A105390(n) < n/2 for n with 1262 < n < a(4)=5230;
A105390(n) > n/2 for n with 5230 < n < a(5)=15804;
A105390(n) < n/2 for n with 15804 < n < a(6)=15814;
A105390(15815)=7908, A105390(a(7))=A105390(15816)=7909;
A105390(n) < n/2 for n with 15816 < n < a(8)=36294;
A105390(n) > n/2 for n with 36294 < n < a(9)=194876; etc.

Prog

(JBASIC)
s$ = "" : c = 0 : d = 0
FOR n = 1 TO 40000
sn$ = str$(n)
IF instr(s$, sn$) > 0 THEN d = d+1 ELSE c = c+1 : s$ = s$ + sn$
IF c = d THEN print n ; ", " ;
NEXT ' Klaus Brockhaus, Aug 15 2007

Crossrefs

Cf. A048991, A048992, A105390, A131982 (numbers n such that A131981(n) = n/2).

Sequence in context: A066402 A243778 A256634 * A319043 A044984 A252576

Adjacent sequences: A105388 A105389 A105390 * A105392 A105393 A105394

Keyword

nonn,base,more

Author

Reinhard Zumkeller, Apr 04 2005

Status

approved