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A064047 Number of numbers only appearing once in 1-to-n multiplication table. 1
1, 2, 3, 3, 4, 5, 6, 6, 5, 6, 7, 8, 9, 10, 11, 10, 11, 12, 13, 13, 14, 15, 16, 17, 15, 16, 15, 15, 16, 17, 18, 17, 18, 19, 20, 20, 21, 22, 23, 24, 25, 26, 27, 27, 28, 29, 30, 30, 26, 26, 27, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 36, 37, 38, 39, 39, 40, 41, 42, 42, 43 (list; graph; refs; listen; history; internal format)
OFFSET

1,2

EXAMPLE

In the 1-to-5 multiplication table, four numbers (1,9,16,25) appear once only. Therefore a(5)=4.

CROSSREFS

Cf. A064048, A057142, A057143, A057144.

Sequence in context: A075699 A112330 A157222 * A111899 A074753 A013928

Adjacent sequences:  A064044 A064045 A064046 * A064048 A064049 A064050

KEYWORD

nonn

AUTHOR

Matthew Somerville (matthew.somerville(AT)trinity.oxford.ac.uk), Aug 24 2001

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Last modified February 16 06:27 EST 2012. Contains 205860 sequences.