cp's OEIS Frontend

A321128 Single-digit numbers in the order in which they first appear in the decimal expansions of prime numbers, followed by the two-digit numbers in the order in which they appear, then the three-digit numbers, and so on.

%I A321128 #14 Oct 30 2018 04:37:33
%S A321128 2,3,5,7,1,9,4,6,8,0,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,
%T A321128 73,79,83,89,97,10,12,27,39,14,49,15,51,57,16,63,18,81,91,93,99,21,22,
%U A321128 33,24,25,26,69,77,28,30,34,35,36,38,40,42,44,45,46,48,87
%N A321128 Single-digit numbers in the order in which they first appear in the decimal expansions of prime numbers, followed by the two-digit numbers in the order in which they appear, then the three-digit numbers, and so on.
%C A321128 This sequence is a variant of A321043.
%C A321128 This sequence establishes a bijection from the positive integers to the nonnegative integers; see A320938 for the inverse.
%C A321128 Prime numbers appear in increasing order.
%H A321128 Rémy Sigrist, <a href="/A321128/b321128.txt">Table of n, a(n) for n = 1..10000</a>
%H A321128 Rémy Sigrist, <a href="/A321128/a321128.png">Colored scatterplot of the first 100000 terms</a>
%H A321128 Rémy Sigrist, <a href="/A321128/a321128_1.png">Scatterplot of the first 100000 terms of the analog for the Euler totient function (A000010)</a>
%H A321128 Rémy Sigrist, <a href="/A321128/a321128.gp.txt">PARI program for A321128</a>
%e A321128 The first terms, alongside the corresponding prime numbers, are:
%e A321128   n   a(n)  Prime
%e A321128   --  ----  -----
%e A321128    1     2      2
%e A321128    2     3      3
%e A321128    3     5      5
%e A321128    4     7      7
%e A321128    5     1     11
%e A321128    6     9     19
%e A321128    7     4     41
%e A321128    8     6     61
%e A321128    9     8     83
%e A321128   10     0    101
%e A321128   11    11     11
%e A321128   12    13     13
%e A321128   ...
%e A321128   30    89     89
%e A321128   31    97     97
%e A321128   32    10    101
%e A321128   33    12    127
%e A321128   34    27    127
%e A321128   35    39    139
%e A321128   36    14    149
%e A321128   37    49    149
%o A321128 (PARI) See Links section.
%Y A321128 Cf. A000010, A000040, A320938 (inverse), A321043.
%K A321128 nonn,base,look
%O A321128 1,1
%A A321128 _Rémy Sigrist_, Oct 27 2018