A109728 A self-describing sequence.

1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9, 10, 10, 12, 12, 14, 14, 16, 16, 18, 18, 20, 21, 21, 23, 23, 25, 25, 27, 27, 29, 29, 31, 32, 32, 34, 34, 36, 36, 38, 38, 40, 41, 41, 43, 43, 45, 45, 47, 47, 49, 49, 51, 52, 52, 54, 54, 56, 56, 58, 58, 60, 61, 61, 63, 63

Offset

0,2

Links

Table of n, a(n) for n=0..71.

Formula

There are a(n) digits having the same parity as a(n) in the interval ]0;a(n)+1[.

Example

Pick the first "4" in the sequence; "4" is even; there are 4 even digits in the interval ]0;5[ -> 2,2,4 and 4.
Take "21", which is odd; there are 21 odd digits in the interval ]0;22[ -> 1 3 3 5 5 7 7 9 9 1 1 1 1 1 1 1 1 1 1 1 and 1 = 21.

Crossrefs

Sequence in context: A373075 A350894 A373069 * A327036 A358854 A330015

Adjacent sequences: A109725 A109726 A109727 * A109729 A109730 A109731

Keyword

base,easy,nonn

Author

Eric Angelini, Aug 09 2005; revised Aug 25 2005

Status

approved