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Search: id:A061900
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| A061900 |
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Triangular numbers that are not square-free. |
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+0
1
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| 28, 36, 45, 120, 136, 153, 171, 276, 300, 325, 351, 378, 496, 528, 630, 666, 780, 820, 990, 1035, 1128, 1176, 1225, 1275, 1431, 1485, 1540, 1596, 1953, 2016, 2080, 2556, 2628, 2775, 2850, 3160, 3240, 3321, 3828, 3916, 4005, 4095, 4560, 4656, 4753, 4851
(list; graph; listen)
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OFFSET
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1,1
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LINKS
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Harry J. Smith, Table of n, a(n) for n=1,...,1000
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EXAMPLE
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36 and 45 are Triangular numbers (A000217) and are not square-free: 36 = (2^2)(3^2), 45 = (3^2)(5).
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PROGRAM
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(PARI) { n=t=0; for (i=1, 1926, t+=i; if (!issquarefree(t), write("b061900.txt", n++, " ", t)) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Jul 28 2009]
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CROSSREFS
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Cf. A000217, A061304.
Sequence in context: A043170 A043950 A167308 this_sequence A048023 A105710 A080983
Adjacent sequences: A061897 A061898 A061899 this_sequence A061901 A061902 A061903
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KEYWORD
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nonn
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AUTHOR
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Asher Auel (asher.auel(AT)reed.edu), May 20 2001
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