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.

Showing 1-6 of 6 results.

A332901 Lexicographically earliest infinite sequence such that a(i) = a(j) => A278222(A332896(i)) = A278222(A332896(j)) for all i, j.

Original entry on oeis.org

1, 1, 2, 1, 2, 2, 3, 1, 1, 2, 4, 2, 3, 3, 3, 1, 4, 1, 5, 2, 2, 4, 6, 2, 1, 3, 2, 3, 5, 3, 7, 1, 3, 4, 8, 1, 6, 5, 4, 2, 7, 2, 9, 4, 2, 6, 10, 2, 1, 1, 5, 3, 9, 2, 11, 3, 4, 5, 12, 3, 10, 7, 3, 1, 2, 3, 13, 4, 5, 8, 14, 1, 12, 6, 2, 5, 2, 4, 15, 2, 1, 7, 16, 2, 3, 9, 6, 4, 13, 2, 17, 6, 6, 10, 18, 2, 14, 1, 4, 1, 15, 5, 19, 3, 3
Offset: 1

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Author

Antti Karttunen, Mar 04 2020

Keywords

Comments

Restricted growth sequence transform of A278222(A332896(n)).
This is a variant of A292583: Instead of runs of numbers of the form 4k+3 encountered on trajectories of the standard Doudna-tree (A005940), this relates to the corresponding trajectories in A332815-tree. See comments in A292583.
For all i, j:
a(i) = a(j) => A053866(i) = A053866(j),
a(i) = a(j) => A332898(i) = A332898(j).

Crossrefs

Cf. A028982 (positions of ones).
Cf. also A292583.

Programs

A332996 a(n) = A332896(A332817(n)).

Original entry on oeis.org

0, 0, 0, 1, 0, 0, 2, 2, 0, 1, 0, 0, 4, 5, 4, 5, 0, 0, 2, 2, 0, 1, 0, 0, 8, 8, 10, 11, 8, 8, 10, 10, 0, 1, 0, 0, 4, 5, 4, 5, 0, 0, 2, 2, 0, 1, 0, 0, 16, 17, 16, 17, 20, 20, 22, 23, 16, 17, 16, 16, 20, 21, 20, 21, 0, 0, 2, 2, 0, 1, 0, 0, 8, 8, 10, 11, 8, 8, 10, 10, 0, 1, 0, 0, 4, 5, 4, 5, 0, 0, 2, 2, 0, 1, 0, 0, 32, 32, 34, 35, 32, 32, 34, 34, 40, 41
Offset: 0

Views

Author

Antti Karttunen, Mar 05 2020

Keywords

Comments

In contrast to similarly constructed A292274, this sequence can be computed directly from the binary expansion of n, without involving primes or their distribution at all.

Crossrefs

Differs from a similarly constructed A292592 for the first time at n=511, where a(511) = 170, while A292592(511) = 171.

Programs

Formula

a(n) = A332896(A332817(n)).
a(n) = n - A332995(n) = n XOR A332995(n).
A000120(a(n)) = A332998(n).

A332898 a(1) = 0, and for n > 1, a(n) = a(A332893(n)) + [n == 3 (mod 4)].

Original entry on oeis.org

0, 0, 1, 0, 1, 1, 2, 0, 0, 1, 3, 1, 2, 2, 2, 0, 3, 0, 4, 1, 1, 3, 5, 1, 0, 2, 1, 2, 4, 2, 6, 0, 2, 3, 3, 0, 5, 4, 3, 1, 6, 1, 7, 3, 1, 5, 8, 1, 0, 0, 4, 2, 7, 1, 4, 2, 3, 4, 9, 2, 8, 6, 2, 0, 1, 2, 10, 3, 4, 3, 11, 0, 9, 5, 1, 4, 1, 3, 12, 1, 0, 6, 13, 1, 2, 7, 5, 3, 10, 1, 4, 5, 5, 8, 5, 1, 11, 0, 3, 0, 12, 4, 14, 2, 2
Offset: 1

Views

Author

Antti Karttunen, Mar 04 2020

Keywords

Comments

Starting from x=n, iterate the map x -> A332893(x) which divides even numbers by 2, and for odd n, changes every 4k+1 prime in the prime factorization to 4k+3 prime and vice versa (except 3 --> 2), like in A332819. a(n) counts the numbers of the form 4k+3 encountered until 1 has been reached. The count includes also n itself if it is of the form 4k+3 (A004767).
In other words, locate the node which contains n in binary tree A332815 and traverse from that node towards the root, counting all numbers of the form 4k+3 that occur on the path.

Crossrefs

Cf. A028982 (positions of zeros).
Cf. also A292377.

Programs

Formula

a(1) = 0, and for n > 1, a(n) = a(A332893(n)) + [n == 3 (mod 4)].
a(n) = A000120(A332896(n)).

A332895 a(1) = 0, a(2) = 1, and for n > 2, a(n) = 2*a(A332893(n)) + [n == 1 (mod 4)].

Original entry on oeis.org

0, 1, 2, 2, 5, 4, 10, 4, 5, 10, 42, 8, 21, 20, 8, 8, 85, 10, 170, 20, 21, 84, 682, 16, 11, 42, 8, 40, 341, 16, 2730, 16, 85, 170, 16, 20, 1365, 340, 40, 40, 5461, 42, 10922, 168, 17, 1364, 43690, 32, 23, 22, 168, 84, 21845, 16, 80, 80, 341, 682, 174762, 32, 87381, 5460, 40, 32, 43, 170, 699050, 340, 1365, 32, 2796202
Offset: 1

Views

Author

Antti Karttunen, Mar 04 2020

Keywords

Crossrefs

Programs

Formula

a(1) = 0, a(2) = 1, and for n > 2, a(n) = 2*a(A332893(n)) + [n == 1 (mod 4)].
For n > 1, a(2n) = 2*a(n).
For n >= 1, a(A108546(n)) = A000975(n); A000120(a(n)) = A332897(n).

A332811 a(n) = A243071(A332808(n)).

Original entry on oeis.org

0, 1, 3, 2, 7, 6, 15, 4, 5, 14, 63, 12, 31, 30, 13, 8, 127, 10, 255, 28, 29, 126, 1023, 24, 11, 62, 9, 60, 511, 26, 4095, 16, 125, 254, 27, 20, 2047, 510, 61, 56, 8191, 58, 16383, 252, 25, 2046, 65535, 48, 23, 22, 253, 124, 32767, 18, 123, 120, 509, 1022, 262143, 52, 131071, 8190, 57, 32, 59, 250, 1048575, 508, 2045, 54, 4194303, 40, 524287, 4094, 21
Offset: 1

Views

Author

Antti Karttunen, Mar 05 2020

Keywords

Crossrefs

Cf. A332817 (inverse permutation).
Cf. also A332215.

Programs

  • PARI
    up_to = 26927;
    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)};
    A243071(n) = if(n<=2, n-1, if(!(n%2), 2*A243071(n/2), 1+(2*A243071(A064989(n)))));
    A332806list(up_to) = { my(v=vector(2), xs=Map(), lista=List([]), p,q,u); v[2] = 3; v[1] = 5; mapput(xs,1,1); mapput(xs,2,2); mapput(xs,3,3);  for(n=4,up_to, p = v[2-(n%2)]; q = nextprime(1+p); while(q%4 != p%4, q=nextprime(1+q)); v[2-(n%2)] = q; mapput(xs,primepi(q),n)); for(i=1, oo, if(!mapisdefined(xs, i, &u), return(Vec(lista)), listput(lista, prime(u)))); };
    v332806 = A332806list(up_to);
    A332806(n) = v332806[n];
    A332808(n) = { my(f=factor(n)); f[,1] = apply(A332806,apply(primepi,f[,1])); factorback(f); };
    A332811(n) = A243071(A332808(n));

Formula

a(n) = A243071(A332808(n)).
For n > 1, a(n) = A054429(A332816(n)).
a(n) = A332895(n) + A332896(n).
a(n) = A332895(n) OR A332896(n) = A332895(n) XOR A332896(n).
A000120(a(n)) = A332899(n).

A332900 Lexicographically earliest infinite sequence such that a(i) = a(j) => f(i) = f(j), where f(n) = 0 if n > 1 and n is a square or twice square, with f(n) = n for all other numbers.

Original entry on oeis.org

1, 2, 3, 2, 4, 5, 6, 2, 2, 7, 8, 9, 10, 11, 12, 2, 13, 2, 14, 15, 16, 17, 18, 19, 2, 20, 21, 22, 23, 24, 25, 2, 26, 27, 28, 2, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 2, 2, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 2, 54, 55, 56, 57, 58, 59, 60, 2, 61, 62, 63, 64, 65, 66, 67, 68, 2, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 2, 85, 2
Offset: 1

Views

Author

Antti Karttunen, Mar 05 2020

Keywords

Comments

For all i, j:
A324400(i) = A324400(j) => a(i) = a(j),
a(i) = a(j) => A292383(i) = A292383(j) => A292583(i) = A292583(j),
a(i) = a(j) => A332896(i) = A332896(j) => A332901(i) = A332901(j).

Crossrefs

Programs

  • PARI
    up_to = 65537;
    rgs_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), u=1); for(i=1, length(invec), if(mapisdefined(om,invec[i]), my(pp = mapget(om, invec[i])); outvec[i] = outvec[pp] , mapput(om,invec[i],i); outvec[i] = u; u++ )); outvec; };
    A332900aux(n) = if((n>1)&&(issquare(n)||issquare(2*n)),0,n);
    v332900 = rgs_transform(vector(up_to,n,A332900aux(n)));
    A332900(n) = v332900[n];
Showing 1-6 of 6 results.