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 A085977 #10 Aug 05 2019 18:17:12 %S A085977 0,1,0,0,0,1,0,0,1,0,1,1,0,1,0,1,0,0,0,0,1,0,1,0,0,0,1,0,0,1,0,1,1,1, %T A085977 0,0,0,1,0,1,0,0,0,1,0,0,0,1,0,0,2,1,0,0,0,1,0,0,0,0,1,1,1,1,2,1,2,2, %U A085977 1,1,2,1,1,2,1,2,1,1,0,0,0,0,1,2,1,1,0,0,0,1,0,0,0,0,0,1,0,0,1,0,0,0,1,0,0 %N A085977 Number of 3's in decimal expansion of prime(n). %H A085977 Reinhard Zumkeller, <a href="/A085977/b085977.txt">Table of n, a(n) for n = 1..10000</a> %e A085977 prime(2) = 3, so a(2)=1 and prime(345) = 2333, so a(345)=3. %t A085977 DigitCount[Prime[Range[110]],10,3] (* _Harvey P. Dale_, Aug 05 2019 *) %o A085977 (Haskell) %o A085977 a085977 = count3 0 . a000040 where %o A085977 count3 c x | d == 3 = if x < 10 then c + 1 else count3 (c + 1) x' %o A085977 | otherwise = if x < 10 then c else count3 c x' %o A085977 where (x', d) = divMod x 10 %o A085977 -- _Reinhard Zumkeller_, Apr 08 2014 %Y A085977 Cf. 0's A085974, 1's A085975, 2's A085976, 4's A085978, 5's A085979, 6's A085980, 7's A085981, 8's A085982, 9's A085983. %K A085977 base,nonn %O A085977 1,51 %A A085977 _Jason Earls_, Jul 06 2003