A316865 - OEIS

A316865

Number of times 4 appears in decimal expansion of n.

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

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OFFSET

0,45

LINKS

Table of n, a(n) for n=0..104.

EXAMPLE

a(0) = 0 since the decimal representation of 0 does not contain the digit 4.

a(4) = 1 since 4 appears once in the decimal expansion of 4.

MATHEMATICA

Array[ DigitCount[#, 10, 4] &, 105, 0]

PROG

(PARI) a(n) = #select(x->x==4, digits(n)); \\ Michel Marcus, Jul 20 2018