A085981 - OEIS

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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

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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'