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A098650 Smallest odd pseudoprime k > b to bases p_i, i.e., the smallest composite number k > b such that p_i^(k-1)-1 is divisible by k, p_i are the prime factors of b and b is squarefree. 6
9, 341, 91, 217, 1105, 25, 561, 15, 21, 561, 1541, 45, 45, 703, 645, 33, 561, 35, 1729, 49, 703, 1729, 561, 45, 561, 1891, 105, 1105, 77, 341, 65, 91, 65, 1729, 1105, 341, 87, 91, 561, 561, 1105, 85, 91, 561, 105, 111, 561, 703, 2465, 91, 561, 105, 781, 561, 91 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

REFERENCES

Ribenboim, P., The New Book of Prime Number Records. New York: Springer-Verlag, p. 100, 1996.

LINKS

Table of n, a(n) for n=1..55.

Index entries for sequences related to pseudoprimes

EXAMPLE

a(n) is the A005117(n). A005117(5) = 6 = 2*3. a(5) = 1105 because 1105 is the smallest psp to both bases 2 and 3.

MATHEMATICA

PrimeFactors[ n_ ] := Flatten[ Table[ # [[ 1 ]], {1} ] & /@ FactorInteger[ n ]]; f[n_] := Block[{k = n + 1}, If[ EvenQ[k], k++ ]; While[ PrimeQ[k] || Union[ PowerMod[ PrimeFactors[n], k - 1, k]] != {1}, k += 2]; k]; f /@ Select[ Range[90], SquareFreeQ[ # ] &]

CROSSREFS

Cf. A007535, A005117, records in A098651 & A098652.

Sequence in context: A152553 A090087 A090085 * A098652 A110695 A157589

Adjacent sequences:  A098647 A098648 A098649 * A098651 A098652 A098653

KEYWORD

nonn

AUTHOR

Robert G. Wilson v, Sep 18 2004

EXTENSIONS

Needs["NumberTheory`"] (no longer needed) removed from Mathematica code by Jean-François Alcover, Dec 04 2013

STATUS

approved

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Last modified April 5 23:04 EDT 2020. Contains 333260 sequences. (Running on oeis4.)