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A307792
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Triangular numbers t(n) such that n / (product of decimal digits of t(n)) is an integer.
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1
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OFFSET
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1,2
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COMMENTS
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The name implies that t(n) must be zeroless. I conjecture 1 and 15 are the only two terms with the property n = product of decimal digits of t(n). Are all terms bigger than 1 divisible by 3?
The next term, if it exists, is > 3.2*10^24. - Giovanni Resta, May 02 2019
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LINKS
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EXAMPLE
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For n = 150, t(150) = 11325, product of decimal digits of t(150) = 30, n / product of decimal digits of t(n) = 150 / 30 = 5 so t(150) = 11325 is in the sequence;
for n = 378, t(378) = 71631, product of decimal digits of t(378) = 126, n / product of decimal digits of t(n) = 378 / 126 = 3 so t(378) = 71631 is in the sequence.
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MATHEMATICA
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idx = Quiet[Select[Range[100000], Divisible[#, Product[j, {j, IntegerDigits[#*(# + 1)/2]}]] &]]; idx*(idx + 1)/2 (* Vaclav Kotesovec, Apr 30 2019 *)
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CROSSREFS
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KEYWORD
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base,nonn,more
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AUTHOR
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STATUS
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approved
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