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A139717 If k is the smallest divisor of n that is >= sqrt(n) then a(n) = k^2 - n. 2
0, 2, 6, 0, 20, 3, 42, 8, 0, 15, 110, 4, 156, 35, 10, 0, 272, 18, 342, 5, 28, 99, 506, 12, 0, 143, 54, 21, 812, 6, 930, 32, 88, 255, 14, 0, 1332, 323, 130, 24, 1640, 7, 1806, 77, 36, 483, 2162, 16, 0, 50, 238, 117, 2756, 27, 66, 8, 304, 783, 3422, 40, 3660, 899, 18, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(p) = p*(p-1) for all primes p. a(n^2) = 0 for all positive integers n.

LINKS

Ivan Neretin, Table of n, a(n) for n = 1..10000

MATHEMATICA

f[n_]:=Module[{m=First[Select[Divisors[n], #>=Sqrt[n]&]]}, m^2-n]; Array[f, 65]  (* Harvey P. Dale, Apr 02 2011 *)

CROSSREFS

Cf. A139716, A033677.

Sequence in context: A057635 A269943 A243015 * A285119 A202535 A138703

Adjacent sequences:  A139714 A139715 A139716 * A139718 A139719 A139720

KEYWORD

nonn

AUTHOR

Leroy Quet, May 01 2008

EXTENSIONS

Extended by Ray Chandler, Jul 01 2009

STATUS

approved

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Last modified January 26 14:08 EST 2020. Contains 331280 sequences. (Running on oeis4.)