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A261322 Non-repunit elements of A261020 in nonincreasing order. 2
21, 31, 41, 51, 61, 71, 81, 91, 421, 931, 3311, 5111, 5511, 7711, 8421, 9731, 9911, 311111, 444111, 711111, 777111, 993311, 8811111, 51111111, 55551111, 91111111, 93333311, 99311111, 99991111, 441111111, 6666611111, 7111111111, 9333311111, 411111111111, 555111111111, 771111111111, 777777111111, 911111111111 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Permutations of digits of all terms in this sequence are in A261020. There are 2403274 such permutations. About 38% (binomial(32,6) = 906192) of these permutations come from a(61) = 99999911111111111111111111111111.

On average, for every number of digits from 1 to 72, there's exactly one element.

LINKS

David A. Corneth, Table of n, a(n) for n = 1..72

EXAMPLE

{1, 3, 9} forms a group under multiplication in Z/mZ for m = 13 and m = 26 (and no other values of m). m is the sum of digits of a term, so we can solve 9*x + 3*y + 1*z in {13, 26} for (x, y, z) >= (1, 1, 1). Solutions are (x, y, z) in {(1, 1, 1), (2, 2, 2), ..., (1, 1, 14)}. A solution (x, y, z) denotes a term starting with x nines, then followed by y threes, and then by z ones.

CROSSREFS

Cf. A261020.

Sequence in context: A079394 A112375 A067599 * A123846 A168000 A031889

Adjacent sequences:  A261319 A261320 A261321 * A261323 A261324 A261325

KEYWORD

nonn,fini,full,base

AUTHOR

David A. Corneth, Aug 14 2015

STATUS

approved

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Last modified November 20 14:54 EST 2019. Contains 329337 sequences. (Running on oeis4.)