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A153357 Numbers n such that the Wolstenholme number A001008(n) is a semiprime. 0
4, 6, 11, 14, 15, 17, 19, 20, 23, 25, 31, 33, 34, 35, 37, 39, 49, 53, 55, 59, 61, 68, 90, 93, 94, 101, 116, 117, 121, 124, 145, 155, 158, 163, 169, 170, 186, 193, 194, 199, 205, 211, 214, 245, 258, 259, 264, 267, 283, 311, 315, 328, 340, 347, 359, 365 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

REFERENCES

R. L. Graham, D. E. Knuth and O. Patashnik, Concrete Mathematics. Addison-Wesley, Reading, MA, 1990, p. 259.

G. H. Hardy and E. M. Wright, An Introduction to the Theory of Numbers. 3rd ed., Oxford Univ. Press, 1954, page 347.

D. E. Knuth, The Art of Computer Programming. Addison-Wesley, Reading, MA, Vol. 1, p. 615

LINKS

Table of n, a(n) for n=1..56.

Hisanori Mishima, Wolstenholme number (n = 1 to 100, n = 101 to 200, n = 201 to 300, n = 301 to 400, n = 401 to 500, n = 501 to 600).

Eric Weisstein's World of Mathematics, Wolstenholme's Theorem, Harmonic Number.

CROSSREFS

Cf. A001008 = Wolstenholme numbers: numerator of harmonic number H(n)=Sum_{i=1..n} 1/i. Cf. A002805, A056903, A067657.

Sequence in context: A247336 A158138 A096833 * A310591 A002732 A144065

Adjacent sequences:  A153354 A153355 A153356 * A153358 A153359 A153360

KEYWORD

hard,nonn

AUTHOR

Alexander Adamchuk, Dec 24 2008

EXTENSIONS

More terms from Sean A. Irvine, Aug 22 2011

Two missing terms added by D. S. McNeil, Aug 23 2011

More terms from Sean A. Irvine, Apr 01 2013

STATUS

approved

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Last modified August 24 02:32 EDT 2019. Contains 326260 sequences. (Running on oeis4.)