A085981 Number of 7's in decimal expansion of prime(n).

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

Offset

1,59

Links

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

Mathematica

DigitCount[Prime[Range[100]], 10, 7] (* Paolo Xausa, Oct 30 2023 *)

Prog

(Haskell)
a085981 = count7 0 . a000040 where
   count7 c x | d == 7    = if x < 10 then c + 1 else count7 (c + 1) x'
              | otherwise = if x < 10 then c else count7 c x'
              where (x', d) = divMod x 10
-- Reinhard Zumkeller, Apr 08 2014

Crossrefs

Cf. 0's A085974, 1's A085975, 2's A085976, 3's A085977, 4's A085978, 5's A085979, 6's A085980, 8's A085982, 9's A085983.

Sequence in context: A334348 A316717 A328831 * A243224 A127324 A083917

Adjacent sequences: A085978 A085979 A085980 * A085982 A085983 A085984

Keyword

base,nonn

Author

Jason Earls, Jul 06 2003

Status

approved