cp's OEIS Frontend

A098955 Numbers with property that the last digit is the length of the number (written in base 10).

%I A098955 #25 Aug 05 2022 07:45:17
%S A098955 1,12,22,32,42,52,62,72,82,92,103,113,123,133,143,153,163,173,183,193,
%T A098955 203,213,223,233,243,253,263,273,283,293,303,313,323,333,343,353,363,
%U A098955 373,383,393,403,413,423,433,443,453,463,473,483,493,503
%N A098955 Numbers with property that the last digit is the length of the number (written in base 10).
%C A098955 Otherwise said: list of n-digit numbers with n+1 appended, for n=0,1,2,... The sequence is obviously finite, since the largest possible digit and thus maximal possible length of a term is 9. The formula confirms that the last and largest term is a(10^8)=999999999. - _M. F. Hasler_, Jan 06 2013
%H A098955 Robert Israel, <a href="/A098955/b098955.txt">Table of n, a(n) for n = 1..10000</a>
%F A098955 a(n) = 10(n-1)+2 = 10n-8 for n=2,...,10,
%F A098955 a(n) = 10(n-1)+3 = 10n-7 for n=11,...,100,
%F A098955 a(n) = 10(n-1)+4 = 10n-6 for n=101,...,1000, and so on,
%F A098955 a(n) = 10(n-1)+k+1 = 10n-(9-k) for 10^(k-1) < n <= 10^k, up to
%F A098955 a(n) = 10(n-1)+9 = 10n-1 for n=10^7+1,...,10^8. - _M. F. Hasler_, Jan 06 2013
%p A098955 1,seq(seq(10*(n-1)+d,n=10^(d-2)+1..10^(d-1)),d=2..4); # _Robert Israel_, Aug 17 2018
%o A098955 (PARI) A098955(n)=n*10-9+#Str(n-1)-(n==1)  \\ _M. F. Hasler_, Jan 06 2013
%o A098955 (Python)
%o A098955 def a(n): s = str(n); return int(s + str(len(s) + int(n != 0)))
%o A098955 print([a(n) for n in range(51)]) # _Michael S. Branicky_, Aug 04 2022
%K A098955 base,easy,nonn,fini
%O A098955 1,2
%A A098955 _Eric Angelini_, Oct 21 2004