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 A176589 #18 Feb 09 2025 00:23:25 %S A176589 1,3,7,13,31,97,103,109,151,181,193,367,409,439,487,523,571,601,613, %T A176589 733,811,823,1069,1117,1279,1483,1489,1579,1597,1789,1831,1867,1897, %U A176589 1939,2161,2203,2239,2251,2269,2281,2437,2503,2509,2539,2659,2671,2689,2953 %N A176589 Numbers k such that both concatenation of divisors of k and reverse concatenation of divisors of k are noncomposite. %C A176589 Numbers k such that both A037278(k) and A176558(k) are noncomposite. %F A176589 Intersection of A176553 and A089374. - _Jason Yuen_, Feb 08 2025 %e A176589 31 is a term; divisors of 31: 1, 31; both concatenation of divisors 131 and reverse concatenation of divisors 311 are noncomposite. %e A176589 1897 is a term; divisors of 1897: 1, 7, 271, 1897; both concatenation of divisors 172711897 and reverse concatenation of divisors 189727171 are noncomposite. %e A176589 Sequence of corresponding values of concatenations of divisors of a(n): 1, 13, 17, 113, 131, 197, ... %e A176589 Sequence of corresponding values of reverse concatenations of divisors of a(n): 1, 31, 71, 131, 311, 971, ... %Y A176589 Cf. A037278, A176558, A176553, A089374, A176590. %K A176589 nonn,base %O A176589 1,2 %A A176589 _Jaroslav Krizek_, Apr 21 2010 %E A176589 Expanded and revised by _Charles R Greathouse IV_, Apr 24 2010