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2n+1 appears (last digit of 2n+1) times .
1

%I #8 Jun 09 2023 15:05:42

%S 1,3,3,3,5,5,5,5,5,7,7,7,7,7,7,7,9,9,9,9,9,9,9,9,9,11,13,13,13,15,15,

%T 15,15,15,17,17,17,17,17,17,17,19,19,19,19,19,19,19,19,19,21,23,23,23,

%U 25,25,25,25,25,27,27,27,27,27,27,27,29,29,29,29,29,29,29,29,29,31,33,33

%N 2n+1 appears (last digit of 2n+1) times .

%H Robert Israel, <a href="/A130175/b130175.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = a(n-1) + a(n-25) - a(n-26) for n > 26. - _Robert Israel_, Jun 09 2023

%p seq((2*m+1)$(2*m+1 mod 10),m=0..100); # _Robert Israel_, Jun 09 2023

%t Table[Table[n,{Mod[n,10]}],{n,1,35,2}]//Flatten (* _Harvey P. Dale_, Apr 24 2018 *)

%Y Cf. A130146.

%K nonn,base

%O 1,2

%A _Paul Curtz_, Aug 05 2007