

A343826


Numbers which are the product of two Sprimes (A057948) in exactly one way.


4



25, 45, 65, 81, 85, 105, 117, 145, 153, 165, 169, 185, 189, 205, 221, 245, 261, 265, 273, 285, 289, 297, 305, 333, 345, 357, 365, 369, 377, 385, 429, 445, 465, 477, 481, 485, 493, 505, 513, 533, 545, 549, 561, 565, 605, 609, 621, 629, 637, 645, 657, 665, 685
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OFFSET

1,1


COMMENTS

There exist numbers which are the product of two Sprimes in exactly 1, 2, and 3 ways; however, it is unknown if any numbers exist which are the product of two Sprimes in exactly 4 ways.


LINKS



FORMULA



EXAMPLE

153 = 9*17 which are both Sprimes, and admits no other Sprime factorizations.


PROG

isok(n) = sumdiv(n, d, (d<=n/d) && is(d) && is(n/d)) == 1; \\ Michel Marcus, May 01 2021


CROSSREFS



KEYWORD

nonn


AUTHOR



STATUS

approved



