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A211455 The number of bases b for which A181780(n) is a Fermat pseudoprime. 6
2, 2, 2, 2, 2, 2, 2, 6, 4, 2, 2, 2, 2, 2, 14, 4, 2, 2, 2, 2, 2, 14, 2, 34, 2, 2, 2, 14, 2, 2, 2, 6, 2, 8, 2, 2, 2, 2, 2, 34, 2, 2, 2, 14, 2, 2, 14, 2, 2, 2, 2, 14, 10, 2, 2, 10, 4, 2, 2, 14, 4, 2, 2, 8, 6, 2, 2, 2, 14, 2, 2, 2, 2, 2, 34, 2, 14, 6, 38, 6, 2, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Sequences A211456 and A211457 give the smallest and largest bases b; A211458 lists all bases.
Every term in this sequence is even. - Geoffrey Critzer, Apr 08 2015
LINKS
FORMULA
a(n) = A063994(m) - 2 for odd m in A181780. a(n) = A063994(m) - 1 for even m in A181780. - Thomas Ordowski, Dec 13 2013
MATHEMATICA
t = {}; n = 1; While[Length[t] < 100, n++; If[! PrimeQ[n], s = Select[Range[2, n-2], PowerMod[#, n-1, n] == 1 &]; If[s != {}, AppendTo[t, {n, Length[s], s}]]]]; Transpose[t][[2]]
f[n_] := If[ PrimeQ@ n, {}, Count[ Table[ PowerMod[k, n - 1, n], {k, 2, n - 2}], 1]] /. {0 -> {}}; Array[f, 237] // Flatten (* Robert G. Wilson v, Apr 08 2015 *)
CROSSREFS
Sequence in context: A244462 A063790 A334510 * A214079 A202742 A248771
KEYWORD
nonn
AUTHOR
T. D. Noe, Apr 13 2012
STATUS
approved

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Last modified March 2 08:26 EST 2024. Contains 370461 sequences. (Running on oeis4.)