A305425 -id:A305425 - cp's OEIS frontend

A305422 GF(2)[X] factorization prime shift towards smaller terms.

1, 1, 2, 1, 4, 2, 3, 1, 6, 4, 7, 2, 11, 3, 8, 1, 16, 6, 13, 4, 5, 7, 22, 2, 19, 11, 12, 3, 14, 8, 25, 1, 50, 16, 29, 6, 31, 13, 28, 4, 37, 5, 38, 7, 24, 22, 41, 2, 9, 19, 32, 11, 26, 12, 47, 3, 44, 14, 55, 8, 59, 25, 10, 1, 20, 50, 61, 16, 21, 29, 118, 6, 67, 31, 88, 13, 110, 28, 53, 4, 69, 37, 18, 5, 64, 38, 73, 7, 94, 24, 87, 22, 43, 41, 52, 2, 91

Offset: 1

Antti Karttunen, Jun 07 2018

nonn

Let a x b stand for the carryless binary multiplication of positive integers a and b, that is, the result of operation A048720(a,b). With n having a unique factorization as f(i) x f(j) x ... x f(k), with 1 <= i <= j <= ... <= k, a(n) = f(i-1) x f(j-1) x ... x f(k-1), where f(0) = 1, and f(n) = A014580(n) for n >= 1.

Antti Karttunen, Table of n, a(n) for n = 1..65537
Index entries for sequences related to polynomials in ring GF(2)[X]

Cf. A000079 (positions of ones), A014580, A091225, A268389, A305419, A305421, A305424 (odd bisection), A305425.

Cf. also A064989, A300840.

A091225(n) = polisirreducible(Pol(binary(n))*Mod(1, 2));
A305419(n) = if(n<3,1, my(k=n-1); while(k>1 && !A091225(k),k--); (k));
A305422(n) = { my(f = subst(lift(factor(Pol(binary(n))*Mod(1, 2))),x,2)); for(i=1,#f~,f[i,1] = Pol(binary(A305419(f[i,1])))); fromdigits(Vec(factorback(f))%2,2); };

For all n >= 1:
a(A305421(n)) = n.
a(A001317(n)) = A000079(n).
A007814(a(n)) = A268389(n).

A304529 a(1) = 0, a(2n) = n, a(2n+1) = a(A305422(2n+1)).

Original entry on oeis.org

0, 1, 1, 2, 2, 3, 1, 4, 3, 5, 1, 6, 1, 7, 4, 8, 8, 9, 1, 10, 2, 11, 11, 12, 1, 13, 6, 14, 7, 15, 1, 16, 25, 17, 7, 18, 1, 19, 14, 20, 1, 21, 19, 22, 12, 23, 1, 24, 3, 25, 16, 26, 13, 27, 1, 28, 22, 29, 1, 30, 1, 31, 5, 32, 10, 33, 1, 34, 2, 35, 59, 36, 1, 37, 44, 38, 55, 39, 13, 40, 2, 41, 9, 42, 32, 43, 1, 44, 47, 45, 1, 46, 19, 47, 26, 48, 1, 49, 50, 50

Offset: 1

Antti Karttunen, Jun 10 2018

nonn

This is GF(2)[X] analog of A246277.
For all i, j: a(i) = a(j) => A278233(i) = A278233(j).
For all i, j: a(i) = a(j) => A305788(i) = A305788(j).

Antti Karttunen, Table of n, a(n) for n = 1..65537
Index entries for sequences operating on GF(2)[X]-polynomials

Cf. A305422, A305425.
Cf. A014580 (positions of 1's), A278233, A305788.
Cf. also A246277.

A091225(n) = polisirreducible(Pol(binary(n))*Mod(1, 2));
A305419(n) = if(n<3,1, my(k=n-1); while(k>1 && !A091225(k),k--); (k));
A305422(n) = { my(f = subst(lift(factor(Pol(binary(n))*Mod(1, 2))),x,2)); for(i=1,#f~,f[i,1] = Pol(binary(A305419(f[i,1])))); fromdigits(Vec(factorback(f))%2,2); };
A304529(n) = if(1==n,0,while(n%2, n = A305422(n)); n/2);

a(1) = 0, a(2n) = n, a(2n+1) = a(A305422(2n+1)).

A305424 Permutation of natural numbers: a(n) = A305422(2*n-1).

Original entry on oeis.org

1, 2, 4, 3, 6, 7, 11, 8, 16, 13, 5, 22, 19, 12, 14, 25, 50, 29, 31, 28, 37, 38, 24, 41, 9, 32, 26, 47, 44, 55, 59, 10, 20, 61, 21, 118, 67, 88, 110, 53, 69, 18, 64, 73, 94, 87, 43, 52, 91, 100, 58, 97, 56, 15, 103, 62, 82, 109, 115, 48, 23, 74, 76, 49, 98, 117, 113, 152, 131, 46, 148, 137, 143, 164, 218, 27, 96, 227, 145, 230, 89, 182, 200

Offset: 1

Antti Karttunen, Jun 08 2018

nonn

Odd bisection of A305422 and A305425.

Cf. A305423 (inverse).
Cf. A014580, A091225, A304522, A305425.
Cf. also A064216.

A091225(n) = polisirreducible(Pol(binary(n))*Mod(1, 2));
A305419(n) = if(n<3,1, my(k=n-1); while(k>1 && !A091225(k),k--); (k));
A305422(n) = { my(f = subst(lift(factor(Pol(binary(n))*Mod(1, 2))),x,2)); for(i=1,#f~,f[i,1] = Pol(binary(A305419(f[i,1])))); fromdigits(Vec(factorback(f))%2,2); };
A305424(n) = A305422(n+n-1);

a(n) = A305422(2*n-1).

cp's OEIS Frontend

A305422 GF(2)[X] factorization prime shift towards smaller terms.

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A304529 a(1) = 0, a(2n) = n, a(2n+1) = a(A305422(2n+1)).

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A305424 Permutation of natural numbers: a(n) = A305422(2*n-1).

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