This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A208259 #14 Nov 26 2024 09:40:22 %S A208259 1,11,101,111,121,131,141,151,161,171,181,191,1001,1011,1021,1031, %T A208259 1041,1051,1061,1071,1081,1091,1101,1111,1121,1131,1141,1151,1161, %U A208259 1171,1181,1191,1201,1211,1221,1231,1241,1251,1261,1271,1281,1291,1301,1311,1321,1331 %N A208259 Numbers starting and ending with digit 1. %C A208259 A000030(a(n)) = a(n) mod 10 = 1. - _Reinhard Zumkeller_, Jul 16 2014 %H A208259 Reinhard Zumkeller, <a href="/A208259/b208259.txt">Table of n, a(n) for n = 1..10000</a> %t A208259 Select[Range[2000], First[IntegerDigits[#]] == 1 && Last[IntegerDigits[#]] == 1 &] (* _Vladimir Joseph Stephan Orlovsky_, Feb 26 2012 *) %o A208259 (Haskell) %o A208259 a208259 n = a208259_list !! (n-1) %o A208259 a208259_list = 1 : map ((+ 1) . (* 10)) a131835_list %o A208259 -- _Reinhard Zumkeller_, Jul 16 2014 %Y A208259 Intersection of A017281 and A131835. Union of A062332 and A208260. %Y A208259 Supersequence of A208262 (numbers with all divisors starting and ending with digit 1). %Y A208259 Cf. A062332 (primes starting and ending with a digit 1), A208260 (nonprime numbers starting and ending with a digit 1). %Y A208259 Cf. A017281, A131835, A000030. %K A208259 nonn,base %O A208259 1,2 %A A208259 _Jaroslav Krizek_, Feb 24 2012