A168004 Numbers n with property that first digit of 8*n = last digit of n.

21, 32, 43, 54, 65, 76, 86, 97, 108, 119, 131, 141, 151, 161, 171, 181, 191, 201, 211, 221, 231, 241, 252, 262, 272, 282, 292, 302, 312, 322, 332, 342, 352, 362, 372, 383, 393, 403, 413, 423, 433, 443, 453, 463, 473, 483, 493, 504, 514, 524, 534, 544, 554

Offset

1,1

Links

G. C. Greubel, Table of n, a(n) for n = 1..1000

Formula

For 1 <= t <= 9, n = 10*s+t is in the sequence iff for some d>=1, t*(10^d-8)/80 <= s <= t*(10^d-8)/10 + (10^d-1)/80. For each d >= 3, there are 10^d/8 such m. - Robert Israel, Jul 04 2016

a(n) - a(n-1) can be 1 : 8*624 = 4992 and 8*625 = 5000. - Altug Alkan, Jul 04 2016

Example

8*21=168, 8*32=256, 8*43=344, 8*54=432, etc.

Maple

select(n -> floor(8*n/10^ilog10(8*n))=n mod 10, [$1..554]); # Robert Israel, Jul 04 2016

Mathematica

Reap[Do[If[IntegerDigits[n][[ -1]]==IntegerDigits[8*n][[1]], Sow[n]], {n, 1000}]][[2, 1]]
Select[Range[800], Last[IntegerDigits[#]]==First[IntegerDigits[8#]]&] (* Harvey P. Dale, Nov 03 2013 *)

Crossrefs

Cf. A167994, A167996, A167997, A167998, A168000, A168001.

Sequence in context: A054282 A095994 A168001 * A118866 A168005 A118535

Adjacent sequences: A168001 A168002 A168003 * A168005 A168006 A168007

Keyword

base,nonn

Author

Zak Seidov, Nov 16 2009

Status

approved