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A366648
Numbers k such that 4^k + 1 is a semiprime.
0
3, 6, 10, 14, 16, 20, 32, 46, 52, 64, 74, 128, 178, 298, 346, 502, 614, 634, 1912, 60394, 92116
OFFSET
1,1
FORMULA
The even terms of A092559 divided by 2. - Max Alekseyev, Jan 04 2024
EXAMPLE
14 is in this sequence because 4^14+1 = 17*15790321 is a semiprime.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Sean A. Irvine, Oct 16 2023
EXTENSIONS
a(19)-a(21) from Max Alekseyev, Jan 04 2024
STATUS
approved