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A093618
Numbers m such that for all k less than m the number of divisors of k*m and m^2 are different.
3
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74
OFFSET
1,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..1800 from Vincenzo Librandi)
FORMULA
A093616(a(n)) = n.
MATHEMATICA
A093616[n_] := For[k = 1, True, k++, If[DivisorSigma[0, k*n] == DivisorSigma[0, n^2], Return[k]]]; Select[Range[100], A093616[#] == # &] (* Jean-François Alcover, Aug 14 2014 *)
PROG
(PARI) is(n) = {my(k = 1, d = numdiv(n^2)); while(k < n && numdiv(k*n) != d, k++); k == n; } \\ Amiram Eldar, Apr 15 2024
CROSSREFS
Complement of A093617.
Sequence in context: A090322 A076084 A151764 * A317257 A242031 A335376
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Apr 06 2004
EXTENSIONS
Corrected by Franklin T. Adams-Watters, Dec 19 2006
STATUS
approved