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A087910 Exponent of the greatest power of 2 dividing the numerator of 2^1/1 + 2^2/2 + 2^3/3 + ... + 2^n/n. 1
1, 2, 2, 5, 8, 5, 5, 13, 9, 10, 10, 12, 12, 12, 12, 22, 17, 18, 18, 21, 22, 21, 21, 27, 25, 26, 26, 27, 27, 27, 27, 40, 33, 34, 34, 37, 39, 37, 37, 48, 41, 42, 42, 44, 44, 44, 44, 54, 49, 50, 50, 53, 54, 53, 53, 58, 57, 59, 62, 58, 58, 58 (list; graph; refs; listen; history; internal format)
OFFSET

1,2

COMMENTS

Problem 9 of the 2002 Sydney University Mathematical Society Problems competition asked for a proof that a(n) tends to infinity with n. While this is immediate from the theory of the 2-adic logarithm, elementary proofs are available

REFERENCES

A. M. Robert, A Course in p-adic Analysis, Springer, 2000; see p. 278.

LINKS

Sydney University Mathematical Society Problems Competition 2002.

EXAMPLE

a(5) = 8 as 2^1/1 + 2^2/2 + 2^3/3 + 2^4/4 + 2^5/5 = 256/15 whose numerator is divisible by 2^8 but not by 2^9.

CROSSREFS

Cf. A108866.

Sequence in context: A193906 A201972 A202396 * A035570 A183928 A126291

Adjacent sequences:  A087907 A087908 A087909 * A087911 A087912 A087913

KEYWORD

easy,nonn

AUTHOR

Robin Chapman (rjc(AT)maths.ex.ac.uk), Oct 17 2003

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Last modified February 15 07:58 EST 2012. Contains 205717 sequences.