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A078936
Smallest divisor of n*(n+1)/2 that is >= sqrt(n*(n+1)/2).
2
1, 3, 3, 5, 5, 7, 7, 6, 9, 11, 11, 13, 13, 15, 12, 17, 17, 19, 19, 15, 21, 23, 23, 20, 25, 27, 21, 29, 29, 31, 31, 24, 33, 35, 30, 37, 37, 39, 30, 41, 41, 43, 43, 33, 45, 47, 47, 42, 35, 51, 39, 53, 53, 45, 44, 42, 57, 59, 59, 61, 61, 63, 48, 52, 55, 67, 67, 51, 69, 71, 71, 73
OFFSET
1,2
COMMENTS
Greater side of integral rectangle with area n*(n+1)/2 having minimal semiperimeter.
FORMULA
a(n) = A033677(A000217(n)).
a(n) = A078934(n) - A078935(n)
a(n)*A078935(n) = A000217(n).
MATHEMATICA
a[n_] := Select[Divisors[n*(n+1)/2], # >= Sqrt[n*(n+1)/2] &, 1][[1]]; Array[a, 100] (* Amiram Eldar, Aug 03 2024 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Dec 17 2002
STATUS
approved