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A125037 Primes of the form 26k+1 generated recursively. Initial prime is 53. General term is a(n) = Min {p is prime; p divides (R^13 - 1)/(R - 1); p == 1 (mod 13)}, where Q is the product of previous terms in the sequence and R = 13*Q. 19
53, 11462027512399586179504472990060461, 25793, 178907, 131, 5669, 3511, 157, 59021, 13070705295701, 547, 79, 424361132339, 126146525792794964042953901, 5889547, 521, 1301, 6249393047, 9829, 2549, 298378081, 29379481, 56993, 1093, 26729 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

All prime divisors of (R^13 - 1)/(R - 1) different from 13 are congruent to 1 modulo 26.

REFERENCES

M. Ram Murty, Problems in Analytic Number Theory, Springer-Verlag, NY, (2001), pp. 208-209.

LINKS

Table of n, a(n) for n=1..25.

N. Hobson, Home page (listed in lieu of email address)

EXAMPLE

a(2) = 11462027512399586179504472990060461 is the smallest prime divisor congruent to 1 mod 26 of (R^13 - 1)/(R - 1) = 11462027512399586179504472990060461, where Q = 53 and R = 13*Q.

MATHEMATICA

a={53}; q=1;

For[n=2, n<=5, n++,

    q=q*Last[a]; r=13*q;

    AppendTo[a, Min[Select[FactorInteger[(r^13-1)/(r-1)][[All, 1]], Mod[#, 26]==1 &]]];

    ];

a (* Robert Price, Jul 16 2015 *)

CROSSREFS

Cf. A000945, A057204-A057208, A051308-A051335, A124984-A124993, A125037-A125045.

Sequence in context: A183793 A145332 A087530 * A101365 A022080 A238935

Adjacent sequences:  A125034 A125035 A125036 * A125038 A125039 A125040

KEYWORD

nonn

AUTHOR

Nick Hobson, Nov 18 2006

EXTENSIONS

More terms from Sean A. Irvine, Jun 24 2011

STATUS

approved

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Last modified March 29 16:45 EDT 2020. Contains 333107 sequences. (Running on oeis4.)