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A106135
Numbers k such that the k-th semiprime == 10 (mod k).
0
1, 2, 4, 12, 14, 64, 79, 81, 83, 84, 85, 6879, 6901, 613419, 613445, 613571, 613605, 58155568, 6384425499, 6384425501, 6384425551, 6384425553, 6384425635, 819217006167, 819217006202, 819217006763, 819217006854, 819217006872
OFFSET
1,2
COMMENTS
a(29) > 10^12. - Lucas A. Brown, Oct 18 2020
EXAMPLE
a(3)=12 is a term because the 12th semiprime (i.e., 34) == 10 (mod 12).
CROSSREFS
Cf. A001358.
Sequence in context: A039564 A297064 A263466 * A067268 A285378 A082458
KEYWORD
nonn,hard,more
AUTHOR
Shyam Sunder Gupta, May 07 2005
EXTENSIONS
a(18) from Donovan Johnson, Oct 29 2008
a(19)-a(28) by Lucas A. Brown, Oct 18 2020
a(1)-a(3) by Lucas A. Brown, Nov 23 2020
STATUS
approved