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A293626 Numbers of the form (2^(2p) + 1)/5, where p is a prime > 5. 0
3277, 838861, 13421773, 3435973837, 54975581389, 14073748835533, 57646075230342349, 922337203685477581, 3777893186295716170957, 967140655691703339764941, 15474250491067253436239053, 3961408125713216879677197517, 16225927682921336339157801028813 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Rotkiewicz proved that all the terms in this sequence are Fermat pseudoprimes to base 2 (A001567).

LINKS

Table of n, a(n) for n=1..13.

Andrzej Rotkiewicz, Sur les formules donnant des nombres pseudopremiers, Colloquium Mathematicae, Vol. 12, No. 1 (1964), pp. 69-72.

EXAMPLE

3277 = (2^(2*7) + 1)/5 is the first term, corresponding to the prime p = 7.

MATHEMATICA

p = Select[Range[7, 60], PrimeQ]; (2^(2p) + 1)/5

CROSSREFS

Cf. A001567, A210454.

Sequence in context: A245482 A244626 A270204 * A152506 A015326 A252074

Adjacent sequences:  A293623 A293624 A293625 * A293627 A293628 A293629

KEYWORD

nonn

AUTHOR

Amiram Eldar, Oct 13 2017

STATUS

approved

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Last modified May 26 05:22 EDT 2019. Contains 323579 sequences. (Running on oeis4.)