A262052 - OEIS

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A262052

Euler pseudoprimes to base 5: composite integers such that abs(5^((n - 1)/2)) == 1 mod n.

217, 781, 1541, 1729, 5461, 5611, 6601, 7449, 7813, 11041, 12801, 13021, 13333, 14981, 15751, 15841, 16297, 21361, 23653, 24211, 25351, 29539, 30673, 38081, 40501, 41041, 44173, 44801, 46657, 47641, 48133, 53971, 56033, 67921, 75361, 79381, 90241, 98173, 100651, 102311

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000 (term 1..65 from Daniel Lignon)

MATHEMATICA

eulerPseudoQ[n_?PrimeQ, b_] = False; eulerPseudoQ[n_, b_] := Block[{p = PowerMod[b, (n - 1)/2, n]}, p == Mod[1, n] || p == Mod[-1, n]]; Select[2 Range[27000] + 1, eulerPseudoQ[#, 5] &] (* Michael De Vlieger, Sep 09 2015, after Jean-François Alcover at A006970 *)

PROG

(PARI) for(n=1, 1e5, if( Mod(5, (2*n+1))^n == 1 || Mod(5, (2*n+1))^n == 2*n && bigomega(2*n+1) != 1 , print1(2*n+1", "))); \\ Altug Alkan, Oct 11 2015

CROSSREFS

Cf. A006970 (base 2), A262051 (base 3), this sequence (base 5), A262053 (base 6), A262054 (base 7), A262055 (base 8).

Sequence in context: A019422 A231558 A101826 * A020251 A320715 A183778

Adjacent sequences: A262049 A262050 A262051 * A262053 A262054 A262055

KEYWORD

nonn

AUTHOR

Daniel Lignon, Sep 09 2015

STATUS

approved