

A031126


Number of proper factorizations of p1^n*p2^3, where p1 and p2 are distinct primes.


1



2, 6, 15, 30, 56, 96, 161, 256, 400, 607, 906, 1324, 1913, 2718, 3823, 5312, 7315, 9972, 13494, 18104, 24131, 31937, 42020, 54947, 71483, 92491, 119119, 152685, 194886, 247692, 313612, 395546, 497153, 622687, 777423, 967524, 1200571
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OFFSET

0,1


LINKS



FORMULA



EXAMPLE

a(0)=2 since 2^3=8 has two proper (i.e. nontrivial) factorizations, 2*4 and 2*2*2. a(1)=6 since 2*3^3 = 54 has the proper factorizations 2*27, 2*3*9, 2*3*3*3, 6*3*3, 6*9, 18*3.  N. J. A. Sloane, May 01 2017


CROSSREFS



KEYWORD

nonn


AUTHOR



EXTENSIONS

Offset changed to 0 and more terms added by Ray Chandler, May 01 2017


STATUS

approved



