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A346138 Sphenic numbers that are the product of Mersenne primes. 0
651, 2667, 11811, 27559, 172011, 761763, 1777447, 2752491, 3120771, 7281799, 11010027, 12189603, 28442407, 32247967, 48758691, 49938051, 113770279, 116522119, 199753347, 466091143, 516026527, 2064117919, 3220807683, 7515217927, 12883304451, 30061043719, 33281679391, 45097156587, 133127479327 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The largest known sphenic number is a term of this sequence.

a(n) == 3 (mod 4) for n >= 1.

LINKS

Table of n, a(n) for n=1..29.

Wikipedia, Sphenic number (lists the largest known sphenic number)

Wikipedia, Mersenne prime

Index to sequences related to prime signature

EXAMPLE

a(1) = 651, since 651 = 3*7*31.

a(2) = 2667, since 2667 = 3*7*127.

a(3) = 11811, since 11811 = 3*31*127.

MATHEMATICA

M = 2^MersennePrimeExponent[Range[12]] - 1; Take[ Union[ Times @@@ Subsets[ M, {3}]], 50]

CROSSREFS

Cf. A007304, A046528, A144856.

Sequence in context: A043605 A255619 A151736 * A010087 A110850 A257715

Adjacent sequences:  A346135 A346136 A346137 * A346139 A346140 A346141

KEYWORD

nonn

AUTHOR

Timothy L. Tiffin, Jul 06 2021

STATUS

approved

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Last modified December 9 07:21 EST 2021. Contains 349627 sequences. (Running on oeis4.)