The OEIS is supported by the many generous donors to the OEIS Foundation.
%I #21 Mar 20 2020 20:08:50
%S 1,11,121,253,1331,2783,5819,11891,14641,30613,35167,45023,64009,
%T 96569,130801,133837,161051,273493,336743,386837,495253,527197,558877,
%U 640343,704099,808841,1035529,1062259,1438811,1472207,1652849,1771561,2221087,3008423,3045449
%N Numbers k such that k | 10^k + 1.
%H Seiichi Manyama, <a href="/A015958/b015958.txt">Table of n, a(n) for n = 1..100</a>
%t Select[Range[15*10^5],PowerMod[10,#,#]==#-1&] (* _Harvey P. Dale_, Oct 01 2017 *)
%Y Solutions to b^k == -1 (mod k): A006521 (b=2), A015949 (b=3), A015950 (b=4), A015951 (b=5), A015953 (b=6), A015954 (b=7), A015955 (b=8), A015957 (b=9), this sequence (b=10), A015960 (b=11), A015961 (b=12), A015963 (b=13), A015965 (b=14), A015968 (b=15), A015969 (b=16).
%Y Column k=10 of A333429.
%K nonn
%O 1,2
%A _Robert G. Wilson v_
%E Corrected by _T. D. Noe_, Oct 31 2006