A089185 Numbers n with following property: suppose n^2 = d1 d2 d3 ...dk in decimal; then d1! + d2! + ... + dk! is a square.

1, 11, 12, 21, 43, 190, 216, 251, 258, 370, 384, 408, 440, 462, 669, 762, 804, 809, 871, 884, 919, 1188, 1519, 1520, 1521, 1790, 1800, 1875, 2305, 2312, 2538, 2997, 3151, 3210, 3362, 3474, 4026, 4561, 5110, 5490, 5521, 5569, 5726, 5762, 5785, 7216, 7521

Offset

1,2

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Example

a(4)=21: 21^2=441, (4!+4!+1!)^(1/2)=7.

Maple

filter:= n -> issqr(add(d!, d=convert(n^2, base, 10))):
select(filter, [$1..10^4]); # Robert Israel, Mar 18 2018

Crossrefs

Sequence in context: A153146 A132359 A131363 * A098754 A098752 A240763

Adjacent sequences: A089182 A089183 A089184 * A089186 A089187 A089188

Keyword

nonn,base

Author

Yalcin Aktar, Dec 07 2003

Extensions

More terms from Yalcin Aktar, Mar 02 2007

Status

approved