A333858 - OEIS

A333858

Numbers that are both Colombian and Brazilian.

7, 20, 31, 42, 64, 75, 86, 108, 110, 121, 132, 143, 154, 165, 176, 187, 198, 209, 211, 222, 244, 255, 266, 288, 299, 310, 312, 323, 334, 345, 356, 378, 400, 411, 413, 424, 435, 446, 468, 490, 501, 512, 514, 525, 536, 558, 580, 591, 602, 615, 626, 637, 648, 670, 681, 692

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

121 is the only square of prime in this sequence.

LINKS

Table of n, a(n) for n=1..56.

Wikipédia, Nombre brésilien (in French).

Index entries for sequences related to Brazilian Numbers.

Index entries for sequences related to Colombian Numbers.

EXAMPLE

20 is a term because it is not of the form m + sum of digits of m for any m < 20, so 20 is Colombian and 20 = (22)_9, so 20 is also Brazilian.

MATHEMATICA

brazQ[n_] := Module[{b = 2, found = False}, While[b < n - 1 && Length[Union[IntegerDigits[n, b]]] > 1, b++]; b < n - 1]; n = 700; Select[Complement[Range[n], Union @ Table[Plus @@ IntegerDigits[k] + k, {k, 1, n}]], brazQ] (* Amiram Eldar, Apr 08 2020 after T. D. Noe at A125134 *)

CROSSREFS

Intersection of A003052 and A125134.

Sequence in context: A055069 A134863 A214924 * A319966 A200773 A269044

Adjacent sequences: A333855 A333856 A333857 * A333859 A333860 A333861

KEYWORD

nonn,base

AUTHOR

Bernard Schott, Apr 08 2020

STATUS

approved