A165071 -id:A165071 - cp's OEIS frontend

A165072 A165071(n)/6.

0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 2, 3, 4, 5, 2, 1, 0, 1, 2, 3, 4, 3, 2, 1, 0, 1, 2, 3, 4, 3, 2, 1, 0, 1, 2, 5, 4, 3, 2, 1, 0, 1, 6, 5, 4, 3, 2, 1, 0, 8, 8, 16, 24, 32, 40, 48, 8, 0, 8, 16, 24, 32, 40, 16, 8, 8, 16, 24, 32, 40, 24, 16, 16, 16, 24, 32, 40, 32, 24, 24, 24, 24, 32, 40, 40, 32, 32, 32, 32

Offset: 0

Joseph Myers, Sep 04 2009

Joseph Myers, Table of n, a(n) for n=0..2401
Index entries for the Kaprekar map

Cf. A165071.

In other bases: A164884 (base 2), A164994 (base 3), A165013 (base 4), A165033 (base 5), A165052 (base 6), A165091 (base 8), A165111 (base 9), A151950 (base 10).

A165086 Consider the base-7 Kaprekar map x->K(x) described in A165071. Sequence gives the smallest number that belongs to a cycle of length n under repeated iteration of this map, or -1 if there is no cycle of length n.

Original entry on oeis.org

0, 144, 1068, 9458722410775248, 9936, 55500, 65945195409025452

Offset: 1

Joseph Myers, Sep 04 2009

Known values (to 100 base-7 digits):
a(1) = 0 (base 10) = 0 (base 7)
a(2) = 144 (base 10) = 264 (base 7)
a(3) = 1068 (base 10) = 3054 (base 7)
a(4) = 9458722410775248 (base 10) = 5544222066654442212 (base 7)
a(5) = 9936 (base 10) = 40653 (base 7)
a(6) = 55500 (base 10) = 320544 (base 7)
a(7) = 65945195409025452 (base 10) = 55332221066554443312 (base 7)
a(9) = 419850417612 (base 10) = 42222166444443 (base 7)
a(10) = 114965566537586468276798389479111631100827277423731225926928273344 (base 10) = 65444444444444444444444443066666666666666666666666532222222222222222222222211 (base 7)
a(11) = 31412208 (base 10) = 530666532 (base 7)
a(12) = 26884299308652 (base 10) = 5443216666443222 (base 7)
a(13) = 894060461610805641013834968 (base 10) = 54444444322106666665544322222222 (base 7)
a(14) = 1591271424672409468790707489057394638817384701224062547077367141620193382944 (base 10) = 65444444444444444444444444444306666666666666666666666666665322222222222222222222222222211 (base 7)
a(17) = 107837050564847832079804652808012 (base 10) = 55444444332221110666655554443322222212 (base 7)
a(24) = 7598644111289477155212 (base 10) = 54443222221066554444432222 (base 7)
a(25) = 18244344524504743400068812 (base 10) = 544432222222106655444444432222 (base 7)

Index entries for the Kaprekar map

Cf. A165071, A165075, A165076, A165078, A165080, A165082.

In other bases: A153881 (base 2), A165008 (base 3), A165028 (base 4), A165047 (base 5), A165067 (base 6), A165106 (base 8), A165126 (base 9), A151959 (base 10).

A151949 a(n) = image of n under the Kaprekar map n -> (n with digits sorted into descending order) - (n with digits sorted into ascending order).

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 9, 0, 9, 18, 27, 36, 45, 54, 63, 72, 18, 9, 0, 9, 18, 27, 36, 45, 54, 63, 27, 18, 9, 0, 9, 18, 27, 36, 45, 54, 36, 27, 18, 9, 0, 9, 18, 27, 36, 45, 45, 36, 27, 18, 9, 0, 9, 18, 27, 36, 54, 45, 36, 27, 18, 9, 0, 9, 18, 27, 63, 54, 45, 36, 27, 18, 9, 0, 9, 18, 72, 63, 54, 45, 36, 27, 18, 9, 0, 9, 81, 72, 63, 54, 45, 36, 27, 18, 9, 0, 99, 99, 198, 297, 396, 495, 594, 693, 792, 891, 99, 0, 99, 198, 297, 396, 495, 594, 693, 792

Offset: 0

N. J. A. Sloane, Aug 18 2009

Entries are multiples of 9 - see A151950.

a(n) = A004186(n) - A004185(n); a(A010785(n)) = 0. - Reinhard Zumkeller, corrected: Mar 23 2015, Jul 09 2013

			For n = 15, a(15) = 51 - 15 = 36. - _Indranil Ghosh_, Feb 01 2017

Indranil Ghosh, Table of n, a(n) for n = 0..20000 (terms 0..1000 from Joseph Myers and Robert G. Wilson v)
H. Hanslik, E. Hetmaniok, I. Sobstyl, et al., Orbits of the Kaprekar's transformations-some introductory facts, Zeszyty Naukowe Politechniki Śląskiej, Seria: Matematyka Stosowana z. 5, Nr kol. 1945; 2015.
M. Kauers and C. Koutschan, Some D-finite and some possibly D-finite sequences in the OEIS, arXiv:2303.02793 [cs.SC], 2023.
R. J. Mathar, Maple code for A151949 and A151959
Joseph Myers, C program for computing sequences related to the Kaprekar map
Joseph Myers, List of cycles under Kaprekar map (all numbers with <= 60 digits; cycles are represented by their smallest value)
Index entries for the Kaprekar map

In other bases: A164884 (base 2), A164993 (base 3), A165012 (base 4), A165032 (base 5), A165051 (base 6), A165071 (base 7), A165090 (base 8), A165110 (base 9). - Joseph Myers, Sep 05 2009
Cf. A151959, A069746, A347688.
Cf. also A004185, A004186, A099009 (fixed points).

a151949 n = a004186 n - a004185 n
-- Reinhard Zumkeller, corrected: Mar 23 2015, Jul 09 2013

f[n_] := Module[{idn = IntegerDigits@n, idns}, idns = Sort@ idn; FromDigits@ Reverse@ idns - FromDigits@ idns]; Table[ f@n, {n, 0, 200}] (* Harvey P. Dale, Aug 18 2009 *)
Flatten[Table[Differences[FromDigits /@ {y = Sort[x = IntegerDigits[n]], Reverse[y]}], {n, 0, 74}]] (* Jayanta Basu, Jul 11 2013 *)

a(n) = {my(d=digits(n)); fromdigits(vecsort(d,,4)) - fromdigits(vecsort(d));} \\ Michel Marcus, Dec 08 2019

def A151949(n):
    return int("".join(sorted(str(n),reverse=True)))-int("".join(sorted(str(n)))) # Indranil Ghosh, Feb 01 2017

More terms from Robert G. Wilson v, Aug 19 2009

More than the usual number of terms are shown in order to distinguish this from similar sequences. - N. J. A. Sloane, Sep 22 2021

A165012 a(n) = image of n under the base-4 Kaprekar map n -> (n with digits sorted into descending order) - (n with digits sorted into ascending order).

Original entry on oeis.org

0, 0, 0, 0, 3, 0, 3, 6, 6, 3, 0, 3, 9, 6, 3, 0, 15, 15, 30, 45, 15, 0, 15, 30, 30, 15, 15, 30, 45, 30, 30, 30, 30, 30, 30, 45, 30, 15, 15, 30, 30, 15, 0, 15, 45, 30, 15, 15, 45, 45, 45, 45, 45, 30, 30, 30, 45, 30, 15, 15, 45, 30, 15, 0, 63, 75, 138, 201, 75, 63, 126, 189, 138, 126

Offset: 0

Joseph Myers, Sep 04 2009

			For n = 11, 11_10 = 23_4. So, a(11) = 32_4 - 23_4 = 14 - 11 = 3. - _Indranil Ghosh_, Feb 02 2017

Indranil Ghosh, Table of n, a(n) for n = 0..16384 (terms 0..1024 from Joseph Myers)
Index entries for the Kaprekar map

Cf. A165013.

In other bases: A164884 (base 2), A164993 (base 3), A165032 (base 5), A165051 (base 6), A165071 (base 7), A165090 (base 8), A165110 (base 9), A151949 (base 10).

b4km[n_]:=Module[{idn4=Sort[IntegerDigits[n,4]]},FromDigits[ Reverse[ idn4],4]-FromDigits[idn4,4]]; Array[b4km,80,0]

cons(m) = {local(b, r); r=0; b=1; for(i=1, matsize(m)[2], r=r+b*m[i]; b=b*4); r}
A165012(n) = {local(m, r); r=[]; m=n; while(m>0, r=concat(m%4, r); m=floor(m/4)); cons(vecsort(r,,0))-cons(vecsort(r,,4))} \\ Michael B. Porter, Nov 05 2009

A165051 a(n) = image of n under the base-6 Kaprekar map n -> (n with digits sorted into descending order) - (n with digits sorted into ascending order).

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 5, 0, 5, 10, 15, 20, 10, 5, 0, 5, 10, 15, 15, 10, 5, 0, 5, 10, 20, 15, 10, 5, 0, 5, 25, 20, 15, 10, 5, 0, 35, 35, 70, 105, 140, 175, 35, 0, 35, 70, 105, 140, 70, 35, 35, 70, 105, 140, 105, 70, 70, 70, 105, 140, 140, 105, 105, 105, 105, 140, 175, 140, 140, 140

Offset: 0

Joseph Myers, Sep 04 2009

			For n = 10, 10_10 = 14_6. So, a(10) = 41_6 - 14_6 = 25 - 10 = 15. - _Indranil Ghosh_, Feb 02 2017

Indranil Ghosh, Table of n, a(n) for n = 0..46656 (terms 0..1296 from Joseph Myers)
Index entries for the Kaprekar map

Cf. A165052.

In other bases: A164884 (base 2), A164993 (base 3), A165012 (base 4), A165032 (base 5), A165071 (base 7), A165090 (base 8), A165110 (base 9), A151949 (base 10).

a[n_] := With[{dd = IntegerDigits[n, 6]}, FromDigits[ReverseSort[dd], 6] - FromDigits[Sort[dd], 6]];
a /@ Range[0, 100] (* Jean-François Alcover, Jan 08 2020 *)

A165090 a(n) is the image of n under the base-8 Kaprekar map n -> (n with digits sorted into descending order) - (n with digits sorted into ascending order).

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 7, 0, 7, 14, 21, 28, 35, 42, 14, 7, 0, 7, 14, 21, 28, 35, 21, 14, 7, 0, 7, 14, 21, 28, 28, 21, 14, 7, 0, 7, 14, 21, 35, 28, 21, 14, 7, 0, 7, 14, 42, 35, 28, 21, 14, 7, 0, 7, 49, 42, 35, 28, 21, 14, 7, 0, 63, 63, 126, 189, 252, 315, 378, 441, 63, 0, 63, 126, 189

Offset: 0

Joseph Myers, Sep 04 2009

			For n = 11, 11_10 = 13_8. So, a(11) = 31_8 - 13_8 = 25 - 11 = 14. - _Indranil Ghosh_, Feb 02 2017

Indranil Ghosh, Table of n, a(n) for n = 0..32768 (terms 0..4096 from Joseph Myers)
Index entries for the Kaprekar map

Cf. A165091.

In other bases: A164884 (base 2), A164993 (base 3), A165012 (base 4), A165032 (base 5), A165051 (base 6), A165071 (base 7), A165110 (base 9), A151949 (base 10).

a[n_] := With[{dd = IntegerDigits[n, 8]}, FromDigits[ReverseSort[dd], 8] - FromDigits[Sort[dd], 8]];
a /@ Range[0, 100] (* Jean-François Alcover, Jan 08 2020 *)

def A165090(n):
    if n==0:return 0
    return int("".join(sorted(oct(n)[2:],reverse=True)),8)-int("".join(sorted(oct(n)[2:])),8) # Indranil Ghosh, Feb 02 2017

A165110 a(n) = image of n under the base-9 Kaprekar map n -> (n with digits sorted into descending order) - (n with digits sorted into ascending order).

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 0, 8, 16, 24, 32, 40, 48, 56, 16, 8, 0, 8, 16, 24, 32, 40, 48, 24, 16, 8, 0, 8, 16, 24, 32, 40, 32, 24, 16, 8, 0, 8, 16, 24, 32, 40, 32, 24, 16, 8, 0, 8, 16, 24, 48, 40, 32, 24, 16, 8, 0, 8, 16, 56, 48, 40, 32, 24, 16, 8, 0, 8, 64, 56, 48, 40, 32, 24, 16, 8

Offset: 0

Joseph Myers, Sep 04 2009

			For n = 11, 11_10 = 12_9. So, a(11) = 21_9 - 12_9 = 19 - 11 = 8. - _Indranil Ghosh_, Feb 02 2017

Indranil Ghosh, Table of n, a(n) for n = 0..59049 (terms 0..6561 from Joseph Myers)
Index entries for the Kaprekar map

Cf. A165111.

In other bases: A164884 (base 2), A164993 (base 3), A165012 (base 4), A165032 (base 5), A165051 (base 6), A165071 (base 7), A165090 (base 8), A151949 (base 10).

a[n_] := With[{dd = IntegerDigits[n, 9]}, FromDigits[ReverseSort[dd], 9] - FromDigits[Sort[dd], 9]];
a /@ Range[0, 100] (* Jean-François Alcover, Jan 08 2020 *)

A165032 a(n) = image of n under the base-5 Kaprekar map n -> (n with digits sorted into descending order) - (n with digits sorted into ascending order).

Original entry on oeis.org

0, 0, 0, 0, 0, 4, 0, 4, 8, 12, 8, 4, 0, 4, 8, 12, 8, 4, 0, 4, 16, 12, 8, 4, 0, 24, 24, 48, 72, 96, 24, 0, 24, 48, 72, 48, 24, 24, 48, 72, 72, 48, 48, 48, 72, 96, 72, 72, 72, 72, 48, 48, 48, 72, 96, 48, 24, 24, 48, 72, 48, 24, 0, 24, 48, 72, 48, 24, 24, 48, 96, 72, 48, 48, 48, 72, 72, 72

Offset: 0

Joseph Myers, Sep 04 2009

			For n = 10, 10_10 = 20_5. So, a(10) = 20_5 - 2_5 = 10 - 2 = 8. - _Indranil Ghosh_, Feb 02 2017

Indranil Ghosh, Table of n, a(n) for n = 0..15625 (terms 0..3125 from Joseph Myers)
Index entries for the Kaprekar map

Cf. A165033.

In other bases: A164884 (base 2), A164993 (base 3), A165012 (base 4), A165051 (base 6), A165071 (base 7), A165090 (base 8), A165110 (base 9), A151949 (base 10).

a[n_] := With[{dd = IntegerDigits[n, 5]}, FromDigits[ReverseSort[dd], 5] - FromDigits[Sort[dd], 5]];
a /@ Range[0, 100] (* Jean-François Alcover, Jan 08 2020 *)

A164993 a(n) = image of n under the base-3 Kaprekar map n -> (n with digits sorted into descending order) - (n with digits sorted into ascending order).

Original entry on oeis.org

0, 0, 0, 2, 0, 2, 4, 2, 0, 8, 8, 16, 8, 0, 8, 16, 8, 8, 16, 16, 16, 16, 8, 8, 16, 8, 0, 26, 32, 58, 32, 26, 52, 58, 52, 58, 32, 26, 52, 26, 0, 26, 52, 26, 32, 58, 52, 58, 52, 26, 32, 58, 32, 26, 52, 58, 64, 58, 52, 58, 64, 58, 52, 58, 52, 58, 52, 26, 32, 58, 32, 26, 64, 58, 52, 58, 32

Offset: 0

Joseph Myers, Sep 04 2009

			For n = 10, 10_10 = 101_3. So, a(10) = 110_3 - 11_3 = 12 - 4 = 8. - _Indranil Ghosh_, Feb 02 2017

Indranil Ghosh, Table of n, a(n) for n = 0..19683 (terms 0..2187 from Joseph Myers)
Index entries for the Kaprekar map

Cf. A164994.

In other bases: A164884 (base 2), A165012 (base 4), A165032 (base 5), A165051 (base 6), A165071 (base 7), A165090 (base 8), A165110 (base 9), A151949 (base 10).

a[n_] := With[{dd = IntegerDigits[n, 3]}, FromDigits[ReverseSort[dd], 3] - FromDigits[Sort[dd], 3]];
a /@ Range[0, 100] (* Jean-François Alcover, Jan 08 2020 *)

A164884 a(n) = image of n under the base-2 Kaprekar map n -> (n with digits sorted into descending order) - (n with digits sorted into ascending order).

Original entry on oeis.org

0, 0, 1, 0, 3, 3, 3, 0, 7, 9, 9, 7, 9, 7, 7, 0, 15, 21, 21, 21, 21, 21, 21, 15, 21, 21, 21, 15, 21, 15, 15, 0, 31, 45, 45, 49, 45, 49, 49, 45, 45, 49, 49, 45, 49, 45, 45, 31, 45, 49, 49, 45, 49, 45, 45, 31, 49, 45, 45, 31, 45, 31, 31, 0, 63, 93, 93, 105, 93, 105, 105, 105, 93, 105, 105

Offset: 0

Joseph Myers, Aug 29 2009

			For n = 17, 17_10 = 10001_2. So, a(17) = 11000_2 - 11_2 = 24 - 3 = 21. - _Indranil Ghosh_, Feb 01 2017

Indranil Ghosh, Table of n, a(n) for n = 0..16384 (terms 0..1024 from Joseph Myers)
Index entries for the Kaprekar map

Cf. A163205, A164885, A164886, A164887.

In other bases: A164993 (base 3), A165012 (base 4), A165032 (base 5), A165051 (base 6), A165071 (base 7), A165090 (base 8), A165110 (base 9), A151949 (base 10).

a[n_] := With[{dd = IntegerDigits[n, 2]}, FromDigits[ReverseSort[dd], 2] - FromDigits[Sort[dd], 2]];
a /@ Range[0, 100] (* Jean-François Alcover, Jan 08 2020 *)

def A164884(n):
    return int("".join(sorted(bin(n)[2:],reverse=True)),2)-int("".join(sorted(bin(n)[2:])),2) # Indranil Ghosh, Feb 01 2017

Cross-references edited by Joseph Myers, Sep 04 2009

cp's OEIS Frontend

A165072 A165071(n)/6.

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A165086 Consider the base-7 Kaprekar map x->K(x) described in A165071. Sequence gives the smallest number that belongs to a cycle of length n under repeated iteration of this map, or -1 if there is no cycle of length n.

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A151949 a(n) = image of n under the Kaprekar map n -> (n with digits sorted into descending order) - (n with digits sorted into ascending order).

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A165012 a(n) = image of n under the base-4 Kaprekar map n -> (n with digits sorted into descending order) - (n with digits sorted into ascending order).

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A165051 a(n) = image of n under the base-6 Kaprekar map n -> (n with digits sorted into descending order) - (n with digits sorted into ascending order).

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A165090 a(n) is the image of n under the base-8 Kaprekar map n -> (n with digits sorted into descending order) - (n with digits sorted into ascending order).

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A165110 a(n) = image of n under the base-9 Kaprekar map n -> (n with digits sorted into descending order) - (n with digits sorted into ascending order).

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A165032 a(n) = image of n under the base-5 Kaprekar map n -> (n with digits sorted into descending order) - (n with digits sorted into ascending order).

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A164993 a(n) = image of n under the base-3 Kaprekar map n -> (n with digits sorted into descending order) - (n with digits sorted into ascending order).

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