A371757 Numbers of the form (4^(p^(k+1)) + 1)/(4^(p^k) + 1), where k >= 1 and p is an odd prime other than 5.
4033, 68719214593, 19341632594266545643831297, 324518553658426708768757511094273, 1684996264962499703367587717863072443065045481313942556034056847361
Offset: 1
Keywords
Links
- Amiram Eldar, Table of n, a(n) for n = 1..18
- Andrzej Mąkowski and Andrzej Rotkiewicz, On pseudoprime numbers of special form, Colloquium Mathematicum, Vol. 2, No. 20 (1969), pp. 269-271; alternative link.
- Wikipedia, Pseudoprime.
- Index entries for sequences related to pseudoprimes.
Programs
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Mathematica
f[p_, k_] := (4^(p^(k + 1)) + 1)/(4^(p^k) + 1); seq[max_] := Module[{s = {}, p = 3, f1, k, addFlag = True}, While[addFlag, If[p == 5, Continue[]]; k = 1; addFlag = False; While[(f1 = f[p, k]) < max, AppendTo[s, f1]; addFlag = True; k++]; p = NextPrime[p, If[p == 3, 2, 1]]]; Sort[s]]; seq[10^80]
Comments