A086015 Number of 7's in decimal expansion of n^2.

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

Offset: 0

Author

Jason Earls, Jul 07 2003

Keywords

• base
• nonn

Links

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

Crossrefs

Cf. 0's A086008, 1's A086009, 2's A086010, 3's A086011, 4's A086012, 5's A086013, 6's A086014, 8's A086016, 9's A086017.

Cf. A269247 for the n^3 analog.

Programs

Mathematica

DigitCount[(Range[0, 100])^2, 10, 7] (* G. C. Greubel, Dec 13 2016 *)

PARI

A086015(n)=#select(d->d==7,digits(n^2)) \\ M. F. Hasler, Feb 21 2016