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A168086
Numbers k such that d(k) is not an isolated number.
1
1, 4, 9, 16, 24, 25, 30, 36, 40, 42, 48, 49, 54, 56, 64, 66, 70, 78, 80, 81, 88, 100, 102, 104, 105, 110, 112, 114, 120, 121, 128, 130, 135, 136, 138, 144, 152, 154, 162, 165, 168, 169, 170, 174, 176, 182, 184, 186, 189, 190, 192, 195, 196, 208, 210, 216, 222
OFFSET
1,2
COMMENTS
A000005 = A167759 U A168086. Where 0,1,3,5,7,8,9,10,11,13,14,15,16,17,19,20,21,22,.. are nonisolated numbers A167707. The nonisolated numbers of divisors of n. The positions of isolated numbers in A000005.
FORMULA
A000005(a(n)) = nonisolated number.
EXAMPLE
A000005(a(1)=1)=1, A000005(a(2)=4)=3, A000005(a(3)=9)=3.
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
Corrected (132, 140, 148 removed, 152 inserted etc.) by R. J. Mathar, Jun 04 2010
STATUS
approved