A086012 - OEIS

A086012

Number of 4's in decimal expansion of n^2.

0, 0, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 2, 0, 0, 0, 0, 0, 1, 0, 1, 2, 2, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 3, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 0, 0, 2, 0, 1, 1, 1, 2, 2, 1, 1, 1, 1, 0, 1, 0, 0, 0, 1, 1, 1, 0, 1, 0, 0, 0, 0, 0, 2, 0, 0, 0, 2, 1, 0, 0, 0, 1, 1, 0, 0, 0, 2, 0, 0

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,13

LINKS

G. C. Greubel, Table of n, a(n) for n = 0..1000

MATHEMATICA

DigitCount[(Range[0, 100])^2, 10, 4] (* G. C. Greubel, Dec 13 2016 *)

PROG

(PARI) A086012(n)=#select(d->d==4, digits(n^2)) \\ M. F. Hasler, Feb 21 2016

CROSSREFS

Cf. 0's A086008, 1's A086009, 2's A086010, 3's A086011, 5's A086013, 6's A086014, 7's A086015, 8's A086016, 9's A086017.

Cf. A269244 for the n^3 analog.