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A118489
Squares for which the product of the digits is a triangular number.
1
0, 1, 16, 25, 49, 100, 400, 576, 900, 1024, 1089, 1521, 1600, 2025, 2209, 2304, 2401, 2500, 2601, 2704, 2809, 3025, 3600, 4096, 4900, 5041, 5625, 6084, 6400, 7056, 8100, 9025, 9409, 9604, 9801, 10000, 10201, 10404, 10609, 10816, 11025, 11236, 12100, 14400
OFFSET
1,3
COMMENTS
Includes all squares not in A052041. - Robert Israel, May 25 2020
LINKS
EXAMPLE
26569 is in the sequence because (1) it is a square, (2) the product of its digits is 2*6*5*6*9=3240 which is a triangular number.
MAPLE
filter:= n -> issqr(1+8*convert(convert(n, base, 10), `*`)):
select(filter, [seq(i^2, i=1..1000)]); # Robert Israel, May 25 2020
MATHEMATICA
Select[Range[0, 120]^2, OddQ[Sqrt[8 (Times@@IntegerDigits[#]) +1]]&] (* Harvey P. Dale, Jul 06 2021 *)
CROSSREFS
Sequence in context: A218439 A192689 A002644 * A110922 A065408 A112392
KEYWORD
base,nonn
AUTHOR
Luc Stevens (lms022(AT)yahoo.com), May 05 2006
EXTENSIONS
1600 inserted by Robert Israel, May 25 2020
STATUS
approved