A167998 - OEIS

%I #6 Jul 05 2016 02:47:56

%S 19,21,31,42,52,63,73,84,94,105,115,126,136,147,157,168,178,189,199,

%T 201,211,221,231,241,251,261,271,281,291,301,311,321,331,341,351,361,

%U 371,381,391,402,412,422,432,442,452,462,472,482,492,502,512,522,532,542

%N Numbers n with property that first digit of 5*n = last digit of n.

%H G. C. Greubel, <a href="/A167998/b167998.txt">Table of n, a(n) for n = 1..1000</a>

%e 5*19=95, 5*21=105, 5*31=155, 5*42=210, etc.

%t Reap[Do[If[IntegerDigits[n][[ -1]]==IntegerDigits[5*n][[1]],Sow[n]],{n,1000}]][[2,1]]

%t Select[Range[100], Last[IntegerDigits[#]] == First[IntegerDigits[5 #]] &] (* _G. C. Greubel_, Jul 03 2016 *)

%Y Cf. A167994, A167996, A167997.

%K base,nonn

%O 1,1

%A _Zak Seidov_, Nov 16 2009