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 A085776 #17 Apr 17 2024 07:59:23 %S A085776 3,10,14,17,18,20,21,26,30,32,33,38,45,46,48,53,54,57,66,70,72,77,81, %T A085776 84,88,98,101,105,110,116,118,122,125,128,132,140,141,142,146,152,158, %U A085776 162,164,170,173,176,177,178,185,190,194,198,204,206,208,210,212,218,222 %N A085776 Numbers k such that k concatenated with k+1 is a semiprime. %H A085776 Paolo Xausa, <a href="/A085776/b085776.txt">Table of n, a(n) for n = 1..10000</a> %e A085776 10 is a term because 1011 = 3*337. %t A085776 Select[Range[300], PrimeOmega[FromDigits[IntegerString[#] <> IntegerString[#+1]]] == 2 &] (* _Paolo Xausa_, Apr 17 2024 *) %Y A085776 Cf. A001358, A001704. %K A085776 base,easy,nonn %O A085776 1,1 %A A085776 _Jason Earls_, Jul 23 2003