A066547 Let N = 123456789101112131415161718..., the concatenation of the natural numbers. a(n) is the n-digit number formed from the digits of N starting from the {n(n-1)/2 +1}th digit. Omit any leading zeros.

1, 23, 456, 7891, 1112, 131415, 1617181, 92021222, 324252627, 2829303132, 33343536373, 839404142434, 4454647484950, 51525354555657, 585960616263646, 5666768697071727, 37475767778798081, 828384858687888990, 9192939495969798991, 101102103104105106, 107108109110111112113

Offset: 1

Author

Amarnath Murthy, Dec 16 2001

Keywords

• nonn
• base

Examples

			1, 23, 456, 7891, 01112, 131415, 1617181, 92021222, 3... becomes 1, 23, 456, 7891, 1112, 131415, 1617181, 92021222, ...
		

Links

• Jason Bard, Table of n, a(n) for n = 1..1000 (first 71 terms from Vincenzo Librandi)

Crossrefs

Cf. A100751, A007376, A033307, A066548.

Cf. A001369, A007923.

Programs

Mathematica

d = Flatten[IntegerDigits /@ Range[90]]; Table[FromDigits[Take[d, {n(n + 1)/2 + 1, (n + 1)(n + 2)/2}]], {n, 0, 17}] (* Robert G. Wilson v, Nov 22 2004 *)

PARI

N=[]; k=0; for(n=1,20, while(#NM. F. Hasler, May 08 2014

Extensions

More terms from Larry Reeves (larryr(AT)acm.org), Dec 18 2001