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A078935 Largest divisor of n*(n+1)/2 that is <= sqrt(n*(n+1)/2). 2
1, 1, 2, 2, 3, 3, 4, 6, 5, 5, 6, 6, 7, 7, 10, 8, 9, 9, 10, 14, 11, 11, 12, 15, 13, 13, 18, 14, 15, 15, 16, 22, 17, 17, 21, 18, 19, 19, 26, 20, 21, 21, 22, 30, 23, 23, 24, 28, 35, 25, 34, 26, 27, 33, 35, 38, 29, 29, 30, 30, 31, 31, 42, 40, 39, 33, 34, 46, 35, 35, 36, 36, 37, 37, 50 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
COMMENTS
Smaller side of integral rectangle with area n*(n+1)/2 having minimal semiperimeter;
a(n) = A033676(A000217(n));
a(n) = A078934(n) - A078936(n); a(n)*A078936(n) = A000217(n).
LINKS
MATHEMATICA
ld[n_]:=Last[Select[Divisors[n], #<=Sqrt[n]&]]; ld/@Accumulate[ Range[ 80]] (* Harvey P. Dale, Jun 19 2021 *)
CROSSREFS
Sequence in context: A303525 A368643 A133948 * A276774 A129768 A210715
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Dec 17 2002
STATUS
approved

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Last modified March 28 14:38 EDT 2024. Contains 371254 sequences. (Running on oeis4.)