A085978 Number of 4's in decimal expansion of prime(n).

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 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, 1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0

Offset: 1

Author

Jason Earls, Jul 06 2003

Keywords

• base
• nonn

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. 0's A085974, 1's A085975, 2's A085976, 3's A085977, 5's A085979, 6's A085980, 7's A085981, 8's A085982, 9's A085983.

Programs

Haskell

a085978 = count4 0 . a000040 where
   count4 c x | d == 4    = if x < 10 then c + 1 else count4 (c + 1) x'
              | otherwise = if x < 10 then c else count4 c x'
              where (x', d) = divMod x 10
-- Reinhard Zumkeller, Apr 08 2014

Mathematica

DigitCount[#,10,4]&/@Prime[Range[110]] (* Harvey P. Dale, May 30 2021 *)