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A364028
Odd squarefree semiprimes s = p*q such that p + q and p - q are not squarefree.
1
65, 77, 115, 141, 159, 295, 301, 303, 319, 329, 403, 427, 473, 481, 515, 533, 581, 589, 629, 655, 671, 679, 703, 713, 717, 785, 835, 869, 871, 943, 965, 1041, 1059, 1099, 1111, 1139, 1145, 1195, 1199, 1207, 1241, 1337, 1339, 1349, 1363, 1387, 1461, 1469, 1501, 1507, 1529
OFFSET
1,1
EXAMPLE
a(1) = 65 = 13*5; 13+5 = 2*3^2, 13-5 = 2^3;
a(2) = 77 = 11*7; 11+7 = 2*3^2, 11-7 = 2^2;
a(3) = 115 = 23*5; 23+5 = 2^2*7, 23-5 = 2*3^2.
PROG
(PARI) forstep (k = 15, 1529, 2, if (omega(k)==2 && bigomega(k)==2, my (F=factorint(k)); if ( !issquarefree(F[2, 1]-F[1, 1]) && !issquarefree(F[2, 1]+F[1, 1]), print1(k, ", "))))
CROSSREFS
KEYWORD
nonn
AUTHOR
Hugo Pfoertner, Jul 01 2023
STATUS
approved