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A376734
Numbers k such that 2*k-1 and 2*k+1 are products of exactly three distinct odd primes (A046389).
2
332, 655, 773, 943, 1007, 1018, 1033, 1046, 1117, 1172, 1277, 1333, 1358, 1369, 1424, 1622, 1667, 1783, 1810, 1828, 1865, 1907, 1928, 2008, 2216, 2252, 2293, 2348, 2404, 2447, 2473, 2518, 2567, 2608, 2645, 2698, 2711, 2726, 2797, 2898, 2942, 2972, 2978, 3031, 3048, 3049
OFFSET
1,1
LINKS
MAPLE
q:= k-> andmap(x-> map(i-> i[2], ifactors(x)[2])=[1$3], [2*k-1, 2*k+1]):
select(q, [$1..4000])[]; # Alois P. Heinz, Oct 18 2024
PROG
(PARI) is_a046389(k) = k%2 && omega(k)==3 && bigomega(k)==3;
is_a376734(n) = is_a046389(2*n-1) && is_a046389(2*n+1)
CROSSREFS
KEYWORD
nonn
AUTHOR
Hugo Pfoertner, Oct 18 2024
STATUS
approved