cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A289152 Ordinal transform of A003434.

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%I A289152 #7 Jun 29 2017 13:47:00
%S A289152 1,1,1,2,1,3,2,3,4,5,1,6,2,7,3,4,1,8,5,6,7,8,2,9,3,10,11,12,4,13,5,6,
%T A289152 7,8,9,14,10,15,11,12,1,16,13,14,15,16,2,17,18,19,3,20,4,17,5,21,22,
%U A289152 23,6,24,7,25,26,8,9,27,10,11,12,28,13,29,14,30,15
%N A289152 Ordinal transform of A003434.
%C A289152 The ordinal transform mentioned is the one described in A002260: the ordinal transform of a sequence b(n) is the sequence t(n) = number of values in b(1),...,b(n) which are equal to b(n).
%C A289152 This sequence has graphical similarities with A286343.
%H A289152 Rémy Sigrist, <a href="/A289152/b289152.txt">Table of n, a(n) for n = 1..10000</a>
%e A289152 The first terms are:
%e A289152     n    A003434(n)      a(n)
%e A289152    --    ----------      ----
%e A289152     1           0          1
%e A289152     2           1          1
%e A289152     3           2          1
%e A289152     4           2          2
%e A289152     5           3          1
%e A289152     6           2          3
%e A289152     7           3          2
%e A289152     8           3          3
%e A289152     9           3          4
%e A289152    10           3          5
%e A289152    11           4          1
%e A289152    12           3          6
%e A289152    13           4          2
%e A289152    14           3          7
%e A289152    15           4          3
%e A289152    16           4          4
%e A289152    17           5          1
%e A289152    18           3          8
%e A289152    19           4          5
%e A289152    20           4          6
%t A289152 With[{nn = 75}, Function[s, Table[Count[#, Last@ #] &@ Take[s, n], {n, nn}]]@ Table[Length@ NestWhileList[EulerPhi, n, # != 1 &] - 1, {n, nn}]] (* _Michael De Vlieger_, Jun 27 2017 *)
%o A289152 (PARI) A003434(n) = for (k=0, oo, if (n==1, return (k), n=eulerphi(n)))
%o A289152 o = vector(10); for (n=1, 100, v=A003434(n); o[1+v]++; print1(o[1+v] ", "))
%Y A289152 Cf. A002260, A003434, A286343.
%K A289152 nonn,look
%O A289152 1,4
%A A289152 _Rémy Sigrist_, Jun 26 2017