A085979 - OEIS

%I #12 Oct 30 2023 09:52:33

%S 0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,

%T 0,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,

%U 0,0,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,1,1,1,1,1,2,1,1,1

%N Number of 5's in decimal expansion of prime(n).

%H Reinhard Zumkeller, <a href="/A085979/b085979.txt">Table of n, a(n) for n = 1..10000</a>

%t DigitCount[Prime[Range[100]],10,5] (* _Paolo Xausa_, Oct 30 2023 *)

%o (Haskell)

%o a085979 = count5 0 . a000040 where

%o    count5 c x | d == 5    = if x < 10 then c + 1 else count5 (c + 1) x'

%o               | otherwise = if x < 10 then c else count5 c x'

%o               where (x', d) = divMod x 10

%o -- _Reinhard Zumkeller_, Apr 08 2014

%Y Cf. 0's A085974, 1's A085975, 2's A085976, 3's A085977, 4's A085978, 6's A085980, 7's A085981, 8's A085982, 9's A085983.

%K base,nonn

%O 1,102

%A _Jason Earls_, Jul 06 2003