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A227092 Numbers whose base-7 sum of digits is 7. 9
13, 19, 25, 31, 37, 43, 55, 61, 67, 73, 79, 85, 91, 103, 109, 115, 121, 127, 133, 151, 157, 163, 169, 175, 199, 205, 211, 217, 247, 253, 259, 295, 301, 349, 355, 361, 367, 373, 379, 385, 397, 403, 409, 415, 421, 427, 445, 451, 457, 463, 469, 493, 499, 505 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

All of the entries are odd.

Subsequence of A016921. - Michel Marcus, Sep 03 2013

In general, the set of numbers with sum of base-b digits equal to b is a subset of { (b-1)*k + 1; k = 2, 3, 4, ... }. - M. F. Hasler, Dec 23 2016

LINKS

Table of n, a(n) for n=1..54.

EXAMPLE

The 7-ary expansion of 13 is (1,6), which has sum of digits 7.

The 7-ary expansion of 103 is (2,0,5), which has sum of digits 7.

10 is not on the list since the 7-ary expansion of 10 is (1,3), which has sum of digits 4 not 7.

MATHEMATICA

Select[Range[600], Total[IntegerDigits[#, 7]]==7&] (* Harvey P. Dale, Aug 18 2014 *)

PROG

(Sage)  [i for i in [0..1000] if sum(Integer(i).digits(base=7))==7]

(PARI) select( is(n)=sumdigits(n, 7)==7, [1..999]) \\ M. F. Hasler, Dec 23 2016

CROSSREFS

Cf. A018900, A187813.

Cf. A226636 (b = 3), A226969 (b = 4), A227062 (b = 5), A227080 (b = 6), A227092 (b = 7), A227095 (b = 8), A227238 (b = 9), A052224 (b = 10).

Sequence in context: A214031 A250293 A058898 * A123840 A258589 A103804

Adjacent sequences:  A227089 A227090 A227091 * A227093 A227094 A227095

KEYWORD

nonn,base

AUTHOR

Tom Edgar, Sep 01 2013

STATUS

approved

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Last modified September 25 20:01 EDT 2020. Contains 337344 sequences. (Running on oeis4.)