A325386 - OEIS

A325386

Numbers n such that for any divisor d of n and some k, A048720(d,k) = n only for trivial cases d=1 and d=n, despite that n is neither prime nor in A014580.

69, 77, 81, 121, 169, 205, 209, 261, 265, 275, 289, 295, 305, 321, 323, 327, 329, 339, 377, 405, 407, 437, 453, 473, 475, 481, 493, 517, 533, 551, 553, 555, 559, 565, 575, 581, 583, 595, 625, 649, 667, 671, 699, 703, 707, 737, 747, 749, 755, 763, 767, 779, 785, 805, 815, 833, 835, 849, 851, 855, 861, 869, 871, 885, 893, 905, 923, 925

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OFFSET

1,1

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..20000

Index entries for sequences related to polynomials in ring GF(2)[X]

PROG

(PARI)

A325560(n) = { my(p = Pol(binary(n))*Mod(1, 2)); sumdiv(n, d, my(q = Pol(binary(d))*Mod(1, 2)); !(p%q)); };

isA325386(n) = (!isprime(n) && !polisirreducible(Pol(binary(n))*Mod(1, 2)) && (2 == A325560(n)));

CROSSREFS

Terms of A325559 not in A257688.