A122111 -id:A122111 - cp's OEIS frontend

A322813 a(n) = A001227(A122111(n)).

1, 1, 1, 2, 1, 2, 1, 2, 3, 2, 1, 2, 1, 2, 3, 2, 1, 4, 1, 2, 3, 2, 1, 2, 4, 2, 3, 2, 1, 4, 1, 2, 3, 2, 4, 4, 1, 2, 3, 2, 1, 4, 1, 2, 3, 2, 1, 2, 5, 6, 3, 2, 1, 4, 4, 2, 3, 2, 1, 4, 1, 2, 3, 2, 4, 4, 1, 2, 3, 6, 1, 4, 1, 2, 6, 2, 5, 4, 1, 2, 3, 2, 1, 4, 4, 2, 3, 2, 1, 4, 5, 2, 3, 2, 4, 2, 1, 8, 3, 6, 1, 4, 1, 2, 6

Offset: 1

Antti Karttunen, Dec 27 2018

nonn

Antti Karttunen, Table of n, a(n) for n = 1..20000
Index entries for sequences computed from indices in prime factorization

Cf. A001227, A122111, A322819.

A001227(n) = numdiv(n>>valuation(n, 2));
A064989(n) = {my(f); f = factor(n); if((n>1 && f[1,1]==2), f[1,2] = 0); for (i=1, #f~, f[i,1] = precprime(f[i,1]-1)); factorback(f)};
A122111(n) = if(1==n,n,prime(bigomega(n))*A122111(A064989(n)));
A322813(n) = A001227(A122111(n));

a(n) = A001227(A122111(n)).

A331595 a(n) = gcd(A122111(n), A241909(n)).

Original entry on oeis.org

1, 2, 4, 3, 8, 3, 16, 5, 3, 3, 32, 5, 64, 3, 18, 7, 128, 15, 256, 5, 18, 3, 512, 7, 3, 3, 5, 5, 1024, 15, 2048, 11, 18, 3, 18, 7, 4096, 3, 18, 7, 8192, 15, 16384, 5, 50, 3, 32768, 11, 3, 45, 18, 5, 65536, 7, 108, 7, 18, 3, 131072, 7, 262144, 3, 50, 13, 108, 15, 524288, 5, 18, 45, 1048576, 11, 2097152, 3, 15, 5, 18, 15, 4194304, 11, 7, 3

Offset: 1

Antti Karttunen, Jan 22 2020

nonn

Antti Karttunen, Table of n, a(n) for n = 1..16384
Index entries for sequences computed from indices in prime factorization

Cf. A122111, A241909, A241916, A331596 (number of distinct prime factors), A331597, A331598, A331599, A331600.

Cf. also A280489, A280491.

Array[If[# == 1, 1, GCD @@ {Block[{k = #, m = 0}, Times @@ Power @@@ Table[k -= m; k = DeleteCases[k, 0]; {Prime@ Length@ k, m = Min@ k}, Length@ Union@ k]] &@ Catenate[ConstantArray[PrimePi[#1], #2] & @@@ #], Function[t, Times @@ Prime@ Accumulate[If[Length@ t < 2, {0}, Join[{1}, ConstantArray[0, Length@ t - 2], {-1}]] + ReplacePart[t, Map[#1 -> #2 & @@ # &, #]]]]@ ConstantArray[0, Transpose[#][[1, -1]]] &[# /. {p_, e_} /; p > 0 :> {PrimePi@ p, e}]} &@ FactorInteger[#]] &, 82] (* Michael De Vlieger, Jan 24 2020, after JungHwan Min at A122111 *)

A064989(n) = {my(f); f = factor(n); if((n>1 && f[1,1]==2), f[1,2] = 0); for (i=1, #f~, f[i,1] = precprime(f[i,1]-1)); factorback(f)};
A122111(n) = if(1==n,n,prime(bigomega(n))*A122111(A064989(n)));
A241909(n) = if(1==n||isprime(n),2^primepi(n),my(f=factor(n),h=1,i,m=1,p=1,k=1); while(k<=#f~, p = nextprime(1+p); i = primepi(f[k,1]); m *= p^(i-h); h = i; if(f[k,2]>1, f[k,2]--, k++)); (p*m));
A331595(n) = gcd(A122111(n), A241909(n));

a(n) = gcd(A122111(n), A241909(n)).

a(A241916(n)) = a(n).

A336125 a(n) = A292385(A122111(n)).

Original entry on oeis.org

0, 1, 2, 2, 4, 4, 8, 5, 5, 8, 16, 10, 32, 16, 10, 10, 64, 8, 128, 20, 20, 32, 256, 20, 8, 64, 11, 40, 512, 16, 1024, 20, 40, 128, 16, 21, 2048, 256, 80, 40, 4096, 32, 8192, 80, 22, 512, 16384, 40, 17, 17, 160, 160, 32768, 16, 32, 80, 320, 1024, 65536, 42, 131072, 2048, 44, 41, 64, 64, 262144, 320, 640, 34, 524288, 41, 1048576, 4096, 20

Offset: 1

Antti Karttunen, Jul 17 2020

nonn

Antti Karttunen, Table of n, a(n) for n = 1..8192
Index entries for sequences computed from indices in prime factorization

Cf. A064989, A122111, A253553, A253566, A292385, A336120, A336123, A336313.

\\ Uses also code given in A336124:
A253553(n) = if(n<=2,1,my(f=factor(n), k=#f~); if(f[k,2]>1,f[k,2]--,f[k,1] = precprime(f[k,1]-1)); factorback(f));
A336125(n) = if(n<=2,n-1,(1==A336124(n))+(2*A336125(A253553(n))));

A064989(n) = {my(f); f = factor(n); if((n>1 && f[1,1]==2), f[1,2] = 0); for (i=1, #f~, f[i,1] = precprime(f[i,1]-1)); factorback(f)};
A122111(n) = if(1==n,n,prime(bigomega(n))*A122111(A064989(n)));
A252463(n) = if(!(n%2),n/2,A064989(n));
A292385(n) = if(n<=2,n-1,(1==(n%4))+(2*A292385(A252463(n))));
A336125(n) = A292385(A122111(n));

a(1) = 0, a(2) = 1, and for n > 2, a(n) = [A122111(n) == 1 (mod 4)] + 2*a(A253553(n)).
a(n) = A292385(A122111(n)).
a(n) = A253566(n) - A336120(n).
A000120(a(n)) = A336123(n).

A253561 Square array read by antidiagonals: A(row,col) = A122111(A246278(row,col)).

Original entry on oeis.org

2, 3, 4, 6, 9, 8, 5, 18, 27, 16, 12, 25, 54, 81, 32, 10, 36, 125, 162, 243, 64, 24, 50, 108, 625, 486, 729, 128, 7, 72, 250, 324, 3125, 1458, 2187, 256, 15, 49, 216, 1250, 972, 15625, 4374, 6561, 512, 20, 75, 343, 648, 6250, 2916, 78125, 13122, 19683, 1024, 48, 100, 375, 2401, 1944, 31250, 8748, 390625, 39366, 59049, 2048, 14, 144, 500, 1875, 16807, 5832, 156250, 26244, 1953125, 118098, 177147, 4096

Offset: 2

Antti Karttunen, Jan 03 2015

If we assume here that a(1) = 1 (but which is not explicitly included because outside of the array), then A253562 gives the inverse permutation.

The top row A253568 contains the same terms as A102750, but in different order.

			The top left corner of the array:
   2,  3,   6,   5,   12,   10,   24,    7,   15,   20,  48,   14,  96,   40,
   4,  9,  18,  25,   36,   50,   72,   49,   75,  100, 144,   98, 288,  200,
   8, 27,  54, 125,  108,  250,  216,  343,  375,  500, 432,  686, 864, 1000,
  16, 81, 162, 625,  324, 1250,  648, 2401, 1875, 2500,1296, 4802,2592, 5000,
  32,243, 486,3125,  972, 6250, 1944,16807, 9375,12500,3888,33614,7776,25000,
...

Antti Karttunen, Table of n, a(n) for n = 2..466; the first 30 antidiagonals of the array

Inverse: A253562.
The leftmost column: A000079. Topmost row: A253568.
Cf. A071178, A122111, A246278, A102750, A253560, A253563.

(define (A253561 n) (A122111 (A246278 n)))

a(n) = A122111(A246278(n)). [As a linear sequence].
Other identities.
A071178(A(row,col)) = row for all col. [All terms on row k have k as the exponent of their largest prime factor.]
A253560(A(row,col)) = A(row+1,col). [For any n >= 2, A253560(n) gives the term which is immediately below n in the same column of this array.]

A253564 Permutation of natural numbers: a(n) = A156552(A122111(n)).

Original entry on oeis.org

0, 1, 3, 2, 7, 5, 15, 4, 6, 11, 31, 9, 63, 23, 13, 8, 127, 10, 255, 19, 27, 47, 511, 17, 14, 95, 12, 39, 1023, 21, 2047, 16, 55, 191, 29, 18, 4095, 383, 111, 35, 8191, 43, 16383, 79, 25, 767, 32767, 33, 30, 22, 223, 159, 65535, 20, 59, 71, 447

Offset: 1

Antti Karttunen, Jan 03 2015

nonn

Note the indexing.

a(n) (n>=2) can be obtained by the composition of a bijection between {2,3,4,...} and the set of integer partitions and a bijection between the set of integer partitions and {1,2,3,4,...}. Explanation on the example n=18. Write 18 = 3*3*2 = 2'*2'*1', where m' = m-th prime. Consider the partition p = (2,2,1) and let b denote the southeast border of the Ferrers board of p. Form a binary number by replacing each east step of b by 1 and each north step of b, with the exception of the last one, by 0: 1010. Its value is a(18) = 10. - Emeric Deutsch, Sep 08 2016.

Alois P. Heinz, Table of n, a(n) for n = 1..10000 (first 1000 terms from Antti Karttunen)
Index entries for sequences that are permutations of the natural numbers

Inverse: A253563.

Cf. A054429, A122111, A156552, A161919, A253566.

a:= proc(n) local i, l, r; r, l:= 0, [0, sort(map(i->
      numtheory[pi](i[1])$i[2], ifactors(n)[2]))[]];
      for i to nops(l)-1 do
        r:= 2*((x-> 2*x+1)@@(l[i+1]-l[i]))(r)
      od; r/2
    end:
seq(a(n), n=1..120);  # Alois P. Heinz, Jul 21 2017

Table[Floor@ Total@ Flatten@ MapIndexed[#1 2^(#2 - 1) &, Flatten[ Table[ 2^(PrimePi@ #1 - 1), {#2}] & @@@ FactorInteger@ #]] &[If[n == 1, 1, Module[{l = #, m = 0}, Times @@ Power @@@ Table[l -= m; l = DeleteCases[l, 0]; {Prime@ Length@ l, m = Min@ l}, Length@ Union@ l]] &@ Catenate[ConstantArray[PrimePi[#1], #2] & @@@ FactorInteger@ n]]], {n, 57}] (* Michael De Vlieger, Sep 08 2016, after JungHwan Min at A122111 *)

(define (A253564 n) (A156552 (A122111 n)))

a(n) = A156552(A122111(n)).
As a composition of other permutations:
a(n) = A054429(A253566(n)).

A322867 a(n) = A000120(A122111(n)).

Original entry on oeis.org

1, 1, 1, 2, 1, 2, 1, 2, 2, 2, 1, 2, 1, 2, 2, 3, 1, 4, 1, 2, 2, 2, 1, 3, 4, 2, 3, 2, 1, 4, 1, 3, 2, 2, 4, 3, 1, 2, 2, 3, 1, 4, 1, 2, 3, 2, 1, 3, 3, 4, 2, 2, 1, 3, 4, 3, 2, 2, 1, 3, 1, 2, 3, 3, 4, 4, 1, 2, 2, 4, 1, 2, 1, 2, 4, 2, 3, 4, 1, 3, 3, 2, 1, 3, 4, 2, 2, 3, 1, 3, 3, 2, 2, 2, 4, 3, 1, 4, 3, 6, 1, 4, 1, 3, 4

Offset: 1

Antti Karttunen, Dec 30 2018

nonn

Antti Karttunen, Table of n, a(n) for n = 1..20000
Antti Karttunen, Data supplement: n, a(n) computed for n = 1..65537
Index entries for sequences related to binary expansion of n
Index entries for sequences computed from indices in prime factorization

Cf. A000120, A001222, A122111, A322863, A322865, A322866.

Array[DigitCount[#, 2, 1] &@ If[# < 3, 1, Block[{k = #, m = 0}, Times @@ Power @@@ Table[k -= m; k = DeleteCases[k, 0]; {Prime@Length@k, m = Min@ k}, Length@ Union@ k]] &@ Catenate[ConstantArray[PrimePi[#1], #2] & @@@ FactorInteger@ #]] &, 105] (* Michael De Vlieger, Dec 31 2018, after JungHwan Min at A122111 *)

A064989(n) = {my(f); f = factor(n); if((n>1 && f[1,1]==2), f[1,2] = 0); for (i=1, #f~, f[i,1] = precprime(f[i,1]-1)); factorback(f)};
A122111(n) = if(1==n,n,prime(bigomega(n))*A122111(A064989(n)));
A322867(n) = hammingweight(A122111(n));

a(n) = A000120(A122111(n)) = A000120(A322865(n)) = A001222(A322863(n)).

A323903 a(n) = A002487(A122111(n)).

Original entry on oeis.org

1, 1, 1, 2, 1, 2, 1, 3, 4, 2, 1, 3, 1, 2, 4, 3, 1, 4, 1, 3, 4, 2, 1, 3, 8, 2, 7, 3, 1, 4, 1, 5, 4, 2, 8, 8, 1, 2, 4, 3, 1, 4, 1, 3, 7, 2, 1, 5, 14, 12, 4, 3, 1, 9, 8, 3, 4, 2, 1, 8, 1, 2, 7, 5, 8, 4, 1, 3, 4, 12, 1, 6, 1, 2, 18, 3, 14, 4, 1, 5, 9, 2, 1, 8, 8, 2, 4, 3, 1, 9, 14, 3, 4, 2, 8, 5, 1, 16, 7, 6, 1, 4, 1, 3, 18

Offset: 1

Antti Karttunen, Feb 09 2019

nonn

Antti Karttunen, Table of n, a(n) for n = 1..16384
Antti Karttunen, Data supplement: n, a(n) computed for n = 1..65537
Index entries for sequences computed from indices in prime factorization
Index entries for sequences related to Stern's sequences

Cf. A002487, A122111, A322865.

Cf. also A323168, A323174, A323902.

A002487(n) = { my(a=1, b=0); while(n>0, if(bitand(n, 1), b+=a, a+=b); n>>=1); (b); }; \\ From A002487
A064989(n) = {my(f); f = factor(n); if((n>1 && f[1,1]==2), f[1,2] = 0); for (i=1, #f~, f[i,1] = precprime(f[i,1]-1)); factorback(f)};
A122111(n) = if(1==n,n,prime(bigomega(n))*A122111(A064989(n)));
A323903(n) = A002487(A122111(n));

a(n) = A002487(A122111(n)) = A002487(A322865(n)).

a(p) = 1 for all primes p.

A334108 a(n) = A331410(A122111(n)).

Original entry on oeis.org

0, 0, 0, 1, 0, 1, 0, 2, 2, 1, 0, 2, 0, 1, 2, 1, 0, 3, 0, 2, 2, 1, 0, 1, 3, 1, 4, 2, 0, 3, 0, 2, 2, 1, 3, 2, 0, 1, 2, 1, 0, 3, 0, 2, 4, 1, 0, 2, 4, 4, 2, 2, 0, 3, 3, 1, 2, 1, 0, 2, 0, 1, 4, 2, 3, 3, 0, 2, 2, 4, 0, 3, 0, 1, 5, 2, 4, 3, 0, 2, 2, 1, 0, 2, 3, 1, 2, 1, 0, 3, 4, 2, 2, 1, 3, 2, 0, 5, 4, 3, 0, 3, 0, 1, 5

Offset: 1

Antti Karttunen, Apr 29 2020

nonn

Antti Karttunen, Table of n, a(n) for n = 1..65537
Index entries for sequences computed from indices in prime factorization

Cf. A008578 (positions of zeros), A064989, A105560, A122111, A322865, A331410, A334107.

A064989(n) = {my(f); f = factor(n); if((n>1 && f[1,1]==2), f[1,2] = 0); for (i=1, #f~, f[i,1] = precprime(f[i,1]-1)); factorback(f)};
A122111(n) = if(1==n,n,prime(bigomega(n))*A122111(A064989(n)));
A331410(n) = if(!bitand(n,n-1),0,1+A331410(n+(n/vecmax(factor(n)[, 1]))));
A334108(n) = A331410(A122111(n));

a(n) = A331410(A122111(n)) = A331410(A322865(n)).

a(n) = A331410(A105560(n)) + a(A064989(n)).

A336321 a(n) = A122111(A225546(n)).

Original entry on oeis.org

1, 2, 3, 4, 7, 5, 19, 6, 9, 11, 53, 10, 131, 23, 13, 8, 311, 15, 719, 22, 29, 59, 1619, 14, 49, 137, 21, 46, 3671, 17, 8161, 12, 61, 313, 37, 25, 17863, 727, 139, 26, 38873, 31, 84017, 118, 39, 1621, 180503, 20, 361, 77, 317, 274, 386093, 33, 71, 58, 733, 3673, 821641, 34, 1742537, 8167, 87, 18, 151, 67, 3681131, 626, 1627, 41, 7754077, 35, 16290047

Offset: 1

Antti Karttunen and Peter Munn, Jul 17 2020

nonn

A122111 and A225546 are both self-inverse permutations of the positive integers based on prime factorizations, and they share further common properties. For instance, they map the prime numbers to powers of 2: A122111 maps the k-th prime to 2^k, whereas A225546 maps it to 2^2^(k-1).

In composing these permutations, this sequence maps the squarefree numbers, as listed in A019565, to the prime numbers in increasing order; and the list of powers of 2 to the "normal" numbers (A055932), as listed in A057335.

			From _Peter Munn_, Jan 04 2021: (Start)
In this set of examples we consider [a(n)] as a function a(.) with an inverse, a^-1(.).
First, a table showing mapping of the powers of 2:
  n     a^-1(2^n) =    2^n =        a(2^n) =
        A001146(n-1)   A000079(n)   A057335(n)
  0             (1)         1            1
  1               2         2            2
  2               4         4            4
  3              16         8            6
  4             256        16            8
  5           65536        32           12
  6      4294967296        64           18
  ...
Next, a table showing mapping of the squarefree numbers, as listed in A019565 (a lexicographic ordering by prime factors):
  n   a^-1(A019565(n))   A019565(n)      a(A019565(n))   a^2(A019565(n))
      Cf. {A337533}      Cf. {A005117}   = prime(n)      = A033844(n-1)
  0              1               1             (1)               (1)
  1              2               2               2                 2
  2              3               3               3                 3
  3              8               6               5                 7
  4              6               5               7                19
  5             12              10              11                53
  6             18              15              13               131
  7            128              30              17               311
  8              5               7              19               719
  9             24              14              23              1619
  ...
As sets, the above columns are A337533, A005117, A008578, {1} U A033844.
Similarly, we get bijections between sets A000290\{0} -> {1} U A070003; and {1} U A335740 -> A005408 -> A066207.
(End)

A122111 composed with A225546.
Cf. A336322 (inverse permutation).
Other sequences used in a definition of this sequence: A000040, A000188, A019565, A248663, A253550, A253560.
Sequences used to express relationship between terms of this sequence: A003159, A003961, A297002, A334747.
Cf. A057335.
A mapping between the binary tree sequences A334866 and A253563.
Lists of sets (S_1, S_2, ... S_j) related by the bijection defined by the sequence: (A000290\{0}, {1} U A070003), ({1} U A001146, A000079, A055932), ({1} U A335740, A005408, A066207), (A337533, A005117, A008578, {1} U A033844).

a(n) = A122111(A225546(n)).
Alternative definition: (Start)
Write n = m^2 * A019565(j), where m = A000188(n), j = A248663(n).
a(1) = 1; otherwise for m = 1, a(n) = A000040(j), for m > 1, a(n) = A253550^j(A253560(a(m))).
(End)
a(A000040(m)) = A033844(m-1).
a(A001146(m)) = 2^(m+1).
a(2^n) = A057335(n).
a(n^2) = A253560(a(n)).
For n in A003159, a(2n) = b(a(n)), where b(1) = 2, b(n) = A253550(n), n >= 2.
More generally, a(A334747(n)) = b(a(n)).
a(A003961(n)) = A297002(a(n)).
a(A334866(m)) = A253563(m).

A336322 a(n) = A225546(A122111(n)).

Original entry on oeis.org

1, 2, 3, 4, 6, 8, 5, 16, 9, 12, 10, 32, 15, 24, 18, 256, 30, 64, 7, 48, 27, 20, 14, 512, 36, 40, 81, 96, 21, 128, 42, 65536, 54, 60, 72, 1024, 35, 120, 45, 768, 70, 192, 105, 80, 162, 28, 210, 131072, 25, 144, 90, 160, 11, 4096, 108, 1536, 135, 56, 22, 2048, 33, 84, 243, 4294967296, 216, 384, 66, 240, 270, 288, 55, 262144, 110, 168, 324, 480, 50

Offset: 1

Antti Karttunen and Peter Munn, Jul 17 2020

nonn

A225546 and A122111 are both self-inverse permutations of the positive integers based on prime factorizations, and they share further common properties. For instance, they map the prime numbers to powers of 2: A225546 maps the k-th prime to 2^2^(k-1), whereas A122111 maps it to 2^k.

In composing these permutations, this sequence maps the list of prime numbers to the squarefree numbers, as listed in A019565; and the "normal" numbers (A055932), as listed in A057335, to ascending powers of 2.

Index entries for sequences that are permutations of the natural numbers

A225546 composed with A122111.
Sorted even bisection: A335738.
Sorted odd bisection (excluding 1): A335740.
Sequences used to express relationship between terms of this sequence: A001222, A003961, A253560, A331590, A350066.
Sequences of sequences (S_1, S_2, ... S_j) with the property a(S_i) = S_{i+1}, or essentially so: (A033844, A000040, A019565), (A057335, A000079, A001146), (A000244, A011764), (A001248, A334110), (A253563, A334866).
The inverse permutation, A336321, lists sequences where the property is weaker (between the sets of terms).

a(A033844(m)) = A000040(m+1). [Offset corrected Peter Munn, Feb 14 2022]
a(A000040(m)) = A019565(m).
a(A057335(m)) = 2^m.
For m >= 1, a(2^m) = A001146(m-1).
a(A253563(m)) = A334866(m).
From Peter Munn, Feb 14 2022: (Start)
a(A253560(n)) = a(n)^2.
For n >= 2, a(A003961(n)) = A331590(a(n), 2^2^(A001222(n)-1)).
a(A350066(n, k)) = A331590(a(n), a(k)).
(End)

cp's OEIS Frontend

A322813 a(n) = A001227(A122111(n)).

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A331595 a(n) = gcd(A122111(n), A241909(n)).

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A336125 a(n) = A292385(A122111(n)).

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A253561 Square array read by antidiagonals: A(row,col) = A122111(A246278(row,col)).

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A253564 Permutation of natural numbers: a(n) = A156552(A122111(n)).

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Maple

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A322867 a(n) = A000120(A122111(n)).

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A323903 a(n) = A002487(A122111(n)).

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A334108 a(n) = A331410(A122111(n)).

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