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 A155148 #17 Jun 30 2025 14:15:12 %S A155148 2,3,10,100,1000,10000,100000,1000000,10000000,100000000,1000000000, %T A155148 10000000000,100000000000,1000000000000,10000000000000, %U A155148 100000000000000,1000000000000000,10000000000000000,100000000000000000,1000000000000000000,10000000000000000000,100000000000000000000,1000000000000000000000 %N A155148 Numbers k such that k^4 has exactly 2 different decimal digits. %p A155148 for n from 1 do convert(convert(n^4,base,10),set) ; if nops(%) = 2 then print(n) ; fi; od: # _R. J. Mathar_, Feb 08 2009 %o A155148 (Python) %o A155148 A155148_list, m = [], [24, -36, 14, -1, 0] %o A155148 for n in range(1,10**6+1): %o A155148 for i in range(4): %o A155148 m[i+1] += m[i] %o A155148 if len(set(str(m[-1]))) == 2: %o A155148 A155148_list.append(n) # _Chai Wah Wu_, Nov 05 2014 %Y A155148 Cf. A155149, A155150 %K A155148 nonn,base %O A155148 1,1 %A A155148 _Dmitry Kamenetsky_, Jan 21 2009 %E A155148 Two more terms from _R. J. Mathar_, Feb 08 2009 %E A155148 a(9)-a(12) from _Charles R Greathouse IV_, Aug 01 2010 %E A155148 More terms from _David A. Corneth_, Jun 30 2025