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%I #9 Jun 10 2018 12:00:01
%S 1,6976,15,35,39,51,95,831,45,88,63,222,135,37888,96,284,117,354,175,
%T 84,153,176,3893,267,210
%N a(n) is the smallest number k such that sigma(k + 2n) = sigma(k) - 2n, or -1 if no such number exists.
%C Even-indexed terms of A304994.
%C If it exists, a(25) > 10^9. Other large (if existent) terms include a(55), a(73), and a(97).
%C Terms a(26)..a(54) are 120, 160, 228, 339, 602, 156, 1393, 425, 279, 1204, 462, 70912, 231, 488, 633, 1099, 575, 228, 369, 1211, 387, 364, 605, 579, 396, 725, 1731, 1146, 455.
%C a(25) > 10^12, if it exists. - _Giovanni Resta_, Jun 10 2018
%F a(n) = A304994(2n).
%Y Cf. A304994.
%K nonn,more
%O 0,2
%A _Jon E. Schoenfield_, Jun 08 2018
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