A346138 Sphenic numbers that are the product of Mersenne primes.

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

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