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A280005 Least prime p such that p^n + 1 is the product of n distinct primes. 1
2, 3, 13, 43, 73, 47, 457, 1697, 109, 8161, 10429, 13183, 30089, 66569, 5281 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Corresponding values of p^n + 1 are 3, 10, 2198, 3418802, 2073071594, 10779215330, 4163067000501310394, ...

LINKS

Table of n, a(n) for n=1..15.

EXAMPLE

a(2) = 3; 3^2 + 1 = 2 * 5.

a(3) = 13; 13^3 + 1 = 2 * 7 * 157.

a(4) = 43; 43^4 + 1 = 2 * 17 * 193 * 521.

PROG

(PARI) a(n) = my(p=2); while (!issquarefree(p^n+1) || omega(p^n+1) != n, p = nextprime(p+1)); p;

CROSSREFS

Cf. A000961, A005117.

Sequence in context: A122719 A106866 A278139 * A235626 A164133 A226938

Adjacent sequences:  A280002 A280003 A280004 * A280006 A280007 A280008

KEYWORD

nonn,more

AUTHOR

Altug Alkan, Feb 24 2017

STATUS

approved

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Last modified September 21 19:39 EDT 2019. Contains 327279 sequences. (Running on oeis4.)