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A123159 Conjectured smallest Sierpinski numbers of the second kind S, base b=2,3,4,5..., where P*S*b^n+1 is composite for all n and S = the multiple of all primes which have multiplicative order base b of 1. 0
78557, 36785490291994693, 66741, 159986 (list; graph; refs; listen; history; internal format)
OFFSET

2,1

COMMENTS

Some values of with base b=2^x+1 for integers x have also been calculated - see the links.

REFERENCES

G. Jaeschke, "On the smallest k such that k * 2n +1 are composite," Math. Comp., 40:181 (1983) 381-384. MR 84k:10006

LINKS

base=2^x+1

base=3

base=5

base=4

EXAMPLE

For base=3, the multiplicative order of 2 base 3 is 1 and therefore the formula is 2*S*3^n+1. Find a covering set of multiplicative orders of primes base b and discover S by trial and error using the Chinese Remainder Theorem.

CROSSREFS

Sequence in context: A038826 A038815 A076336 * A184230 A186612 A180973

Adjacent sequences:  A123156 A123157 A123158 * A123160 A123161 A123162

KEYWORD

hard,more,nonn

AUTHOR

Robert Smith (robert_smith44(AT)hotmail.com), Oct 02 2006

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Last modified February 16 21:17 EST 2012. Contains 205971 sequences.