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A066561
a(n) is the smallest triangular number divisible by n.
6
1, 6, 3, 28, 10, 6, 21, 120, 36, 10, 55, 36, 78, 28, 15, 496, 136, 36, 171, 120, 21, 66, 253, 120, 300, 78, 351, 28, 406, 120, 465, 2016, 66, 136, 105, 36, 666, 190, 78, 120, 820, 210, 903, 528, 45, 276, 1081, 528, 1176, 300, 153, 780, 1378, 378, 55, 1176, 171
OFFSET
1,2
COMMENTS
See A344005 for an efficient algorithm. - N. J. A. Sloane, Jul 13 2021
FORMULA
a(n) = A000217(A011772(n)). - Bill McEachen, Dec 28 2021
PROG
(PARI) { for (n=1, 1000, s=0; b=0; while (b==0, s++; t=s*(s+1)/2; if (t%n == 0, b=1)); write("b066561.txt", n, " ", t) ) } \\ Harry J. Smith, Mar 05 2010
CROSSREFS
KEYWORD
nonn
AUTHOR
Amarnath Murthy, Dec 17 2001
EXTENSIONS
More terms from Naohiro Nomoto, Dec 26 2001
STATUS
approved