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A202779 Least k such that x*k - 1 produces primes for x=1..n and composite for x=n+1. 1
8, 3, 4, 1410, 6, 154770, 5246010, 2894220, 407874180, 214580145780, 9448481062020, 247236503934420, 2545206711847800, 18178612369988250180, 53792264108455702830 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

REFERENCES

Wacław Sierpiński, Czym sie zajmuje teoria liczb. Warsaw: PW "Wiedza Powszechna", 1957, pp. 88-89.

LINKS

Table of n, a(n) for n=1..15.

MATHEMATICA

Table[k = 3; While[i = 1; While[i <= n && PrimeQ[i*k - 1], i++]; i <= n || PrimeQ[i*k - 1], k++]; k, {n, 8}]

CROSSREFS

Another version of A088651.

Sequence in context: A021549 A013665 A209059 * A199440 A199293 A110234

Adjacent sequences:  A202776 A202777 A202778 * A202780 A202781 A202782

KEYWORD

more,nonn

AUTHOR

Arkadiusz Wesolowski, Jan 06 2012

STATUS

approved

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Last modified October 16 08:44 EDT 2019. Contains 328052 sequences. (Running on oeis4.)