login
A305718
a(n) is the smallest number k such that sigma(k + 2n) = sigma(k) - 2n, or -1 if no such number exists.
0
1, 6976, 15, 35, 39, 51, 95, 831, 45, 88, 63, 222, 135, 37888, 96, 284, 117, 354, 175, 84, 153, 176, 3893, 267, 210
OFFSET
0,2
COMMENTS
Even-indexed terms of A304994.
If it exists, a(25) > 10^9. Other large (if existent) terms include a(55), a(73), and a(97).
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.
a(25) > 10^12, if it exists. - Giovanni Resta, Jun 10 2018
FORMULA
a(n) = A304994(2n).
CROSSREFS
Cf. A304994.
Sequence in context: A234111 A184228 A050225 * A237237 A251651 A050673
KEYWORD
nonn,more
AUTHOR
Jon E. Schoenfield, Jun 08 2018
STATUS
approved