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 A085975 #12 Oct 30 2023 11:33:18 %S A085975 0,0,0,0,2,1,1,1,0,0,1,0,1,0,0,0,0,1,0,1,0,0,0,0,0,2,1,1,1,2,1,2,1,1, %T A085975 1,2,1,1,1,1,1,2,2,1,1,1,2,0,0,0,0,0,1,1,0,0,0,1,0,1,0,0,0,2,1,1,1,0, %U A085975 0,0,0,0,0,0,0,0,0,0,1,0,1,1,1,0,0,0,0,0,1,0,0,0,0,1,0,0,0,1,0,1,0,0,0,0,1 %N A085975 Number of 1's in decimal expansion of prime(n). %H A085975 Reinhard Zumkeller, <a href="/A085975/b085975.txt">Table of n, a(n) for n = 1..10000</a> %e A085975 prime(5) = 11, so a(5)=2 and prime(1242) = 10111, so a(1242)=4. %t A085975 DigitCount[Prime[Range[100]],10,1] (* _Paolo Xausa_, Oct 30 2023 *) %o A085975 (Haskell) %o A085975 a085975 = count1 0 . a000040 where %o A085975 count1 c x | d == 1 = if x < 10 then c + 1 else count1 (c + 1) x' %o A085975 | otherwise = if x < 10 then c else count1 c x' %o A085975 where (x', d) = divMod x 10 %o A085975 -- _Reinhard Zumkeller_, Apr 08 2014 %Y A085975 Cf. 0's A085974, 2's A085976, 3's A085977, 4's A085978, 5's A085979, 6's A085980, 7's A085981, 8's A085982, 9's A085983. %K A085975 base,nonn %O A085975 1,5 %A A085975 _Jason Earls_, Jul 06 2003