A371666 Composite numbers which equal the reverse of the concatenation of their ascending ordered prime factors, with repetition, when written in binary.
623, 78205, 101239, 80073085, 1473273719
Offset: 1
Examples
101239 is a term as 101239_10 = 29_10 * 3491_10 = 11101_2 * 110110100011_2 = "11101110110100011"_2 which when reversed is "11000101101110111"_2 = 101239_10.
Programs
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Python
from itertools import count, islice from sympy import factorint def A371666_gen(startvalue=4): # generator of terms >= startvalue for n in count(max(startvalue,4)): f = factorint(n) if sum(f.values()) > 1: c = 0 for p in sorted(f,reverse=True): a, q = p.bit_length(), int(bin(p)[:1:-1],2) for _ in range(f[p]): c = (c<
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