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 A178958 Numbers n from A181780 that are not in A181781. 0
 15, 28, 35, 39, 51, 52, 55, 63, 66, 70, 75, 76, 87, 95, 99, 111, 112, 115, 119, 123, 124, 130, 135, 143, 147, 148, 154, 155, 159, 171, 172, 176, 183, 186, 187, 190, 195, 196, 203, 207, 208, 215, 219, 232, 235, 238, 244, 246, 255, 267, 268, 275, 276, 279, 280, 286, 287, 291, 292, 295, 299 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Numbers that are Fermat pseudoprimes to some base a (2<=a<=n-2) not Euler pseudoprimes to any base a (2<=a<=n-2). LINKS EXAMPLE 4^(15-1) == 1 (mod 15), but 4^((15-1)/2) == 4 (mod 15) PROG (PARI) fsp(n)= { /* whether n is Fermat pseudoprime to any base a where 2<=a<=n-2 */     for (a=2, n-2,         if ( gcd(a, n)!=1, next() );         if ( (Mod(a, n))^(n-1)==+1, return(1) )     );     return(0); } esp(n)= { /* whether n is Euler pseudoprime to any base a where 2<=a<=n-2 */     local(w);     if ( n%2==0, return(0) );     for (a=2, n-2,         if ( gcd(a, n)!=1, next() );         w = abs(component((Mod(a, n))^((n-1)/2), 2));         if ( (w==1) || (w==n-1), return(1) )     );     return(0); } for(n=3, 300, if(isprime(n), next()); if( fsp(n) && (!esp(n)) , print1(n, ", ") ); ); CROSSREFS Sequence in context: A073766 A223449 A031334 * A099808 A291054 A134621 Adjacent sequences:  A178955 A178956 A178957 * A178959 A178960 A178961 KEYWORD nonn AUTHOR Karsten Meyer, Dec 31 2010 STATUS approved

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Last modified July 23 19:17 EDT 2021. Contains 346259 sequences. (Running on oeis4.)