The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 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 T. D. Noe, Table of n, a(n) for n = 1..10000 Index entries for sequences related to pseudoprimes 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 Cf. A181780, A211456, A211457, A211458. Sequence in context: A244462 A063790 A334510 * A214079 A202742 A248771 Adjacent sequences: A211452 A211453 A211454 * A211456 A211457 A211458 KEYWORD nonn AUTHOR T. D. Noe, Apr 13 2012 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

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