A337208 Indices m of repunits R_m that are Colombian (or self) numbers.

1, 4, 6, 17, 28, 39, 50, 61, 72, 83, 94, 109, 120, 131, 142, 153, 164, 175, 186, 197, 199, 210, 221, 232, 243, 254, 265, 276, 287, 298, 300, 311, 322, 333, 344, 355, 366, 377, 388, 399, 401, 412, 423, 434, 445, 456, 467, 478, 489, 500, 502, 513, 524, 535, 546, 557

Offset

1,2

Links

David A. Corneth, Table of n, a(n) for n = 1..10000

Prog

(PARI) upto(n)= {my(res = List()); for(i = 1, n, if(is(i), listput(res, i); print1(i", "))); res}
is(n) = {c = 10^n \ 9; is_A003052(c)}
is_A003052(n)={for(i=1, min(n\2, 9*#digits(n)), sumdigits(n-i)==i && return); n} \\ from M. F. Hasler, Mar 20 2011

Crossrefs

Cf. A002275 (repunits), A003052 (Colombian (or self)), A004022 (repunit primes), A004023 (indices of repunit primes), complement of A337139.

Sequence in context: A024305 A342231 A320245 * A034492 A125691 A302878

Adjacent sequences: A337205 A337206 A337207 * A337209 A337210 A337211

Keyword

nonn,base

Author

David A. Corneth, Aug 19 2020

Status

approved