A066580 Let N = 123456789123456789123456789..., with the digits from 1 to 9 repeated indefinitely. Then a(n) is the n-digit number formed from the digits starting at the {n(n-1)/2 +1}-th position of N, read backwards if n is even.

1, 32, 456, 1987, 23456, 321987, 4567891, 98765432, 123456789, 1987654321, 23456789123, 654321987654, 7891234567891, 65432198765432, 789123456789123, 1987654321987654, 23456789123456789, 987654321987654321

Offset

1,2

Links

Table of n, a(n) for n=1..18.

Example

a(3) = 456, the 3-digit number formed from the 4th digit onwards of N.
a(6) = 321987, the reversed 6-digit number formed from the 16th digit of N.

Crossrefs

Sequence in context: A274802 A274748 A283811 * A076070 A133348 A010837

Adjacent sequences: A066577 A066578 A066579 * A066581 A066582 A066583

Keyword

base,easy,nonn

Author

Amarnath Murthy, Dec 20 2001

Extensions

More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 01 2003

Status

approved