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A194946 Odd non-Carmichael numbers with increasing numbers of bases to which they are pseudoprimes. 4
9, 15, 45, 65, 91, 231, 325, 341, 481, 703, 1541, 1891, 2701, 5461, 6533, 8321, 11041, 12403, 18721, 30889, 38503, 49141, 68101, 79003, 88561, 88831, 104653, 137149, 146611, 176149, 188191, 218791, 226801, 269011, 286903, 385003, 493697, 497503, 563473 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

A141768 is the analog using the Rabin-Miller test rather than the Fermat test. The infinitude of that sequence implies that this sequence is likewise infinite.

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..659

Index entries for sequences related to pseudoprimes

PROG

(PARI) bases(n)=my(f=factor(n)[, 1]); n--; prod(i=1, #f, gcd(f[i]-1, n))

Korselt(n)=my(f=factor(n)); for(i=1, #f[, 1], if(f[i, 2]>1||(n-1)%(f[i, 1]-1), return(0))); 1

r=0; p=5; forprime(q=7, 1e7, forstep(n=p+2, q-2, 2, if(bases(n)>r&&!Korselt(n), r=bases(n); print1(n", "))); p=q) \\ Charles R Greathouse IV, Sep 14 2011

CROSSREFS

Cf. A195327 (number of bases).

Cf. A141768.

Sequence in context: A193579 A274757 A146789 * A020172 A020174 A020315

Adjacent sequences:  A194943 A194944 A194945 * A194947 A194948 A194949

KEYWORD

nonn

AUTHOR

Charles R Greathouse IV, Sep 13 2011

STATUS

approved

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Last modified July 6 23:56 EDT 2020. Contains 335484 sequences. (Running on oeis4.)