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 1-3 of 3 results.

A341353 Greatest k such that 3^k divides A156552(n); the 3-adic valuation of A156552(n).

Original entry on oeis.org

0, 0, 1, 0, 0, 0, 0, 1, 2, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 2, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 3, 0, 0, 1, 1, 0, 0, 0, 0, 0, 3, 0, 0, 1, 0, 0, 0, 0, 0, 2, 0, 1, 0, 0, 0, 0, 1, 0, 2, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 1, 1, 0, 3, 3, 0, 2, 2, 0, 0, 2, 0, 0, 0, 0, 0, 1, 0, 2, 0, 0
Offset: 2

Views

Author

Antti Karttunen, Feb 14 2021

Keywords

Crossrefs

Cf. A007949, A156552, A329609 (positions of nonzeros), A329903, A341354 (even bisection), A341355.
Cf. also A055396 (the 2-adic valuation + 1), A292251.

Programs

  • PARI
    A007949(n) = valuation(n,3);
    A156552(n) = { my(f = factor(n), p2 = 1, res = 0); for(i = 1, #f~, p = 1 << (primepi(f[i, 1]) - 1); res += (p * p2 * (2^(f[i, 2]) - 1)); p2 <<= f[i, 2]); res };
    A341353(n) = A007949(A156552(n));

Formula

a(n) = A007949(A156552(n)).
a(p) = 0 for all primes p.
a(n^2) > 0 for all n >= 2.
a(n) > 0 iff A329903(n) = 0.

A341354 Greatest k such that 3^k divides A156552(2*n); number of trailing 1-digits in the ternary expansion of A156552(n).

Original entry on oeis.org

0, 1, 0, 0, 2, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 0, 1, 3, 0, 1, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 1, 2, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 3, 2, 0, 2, 0, 0, 1, 2, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 1, 2, 0, 0, 0, 4, 1, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 1, 2, 1, 0, 0, 0, 4, 0, 0
Offset: 1

Views

Author

Antti Karttunen, Feb 14 2021

Keywords

Comments

The 3-adic valuation of A156552(2*n).

Crossrefs

Even bisection of A341353.
Cf. A329604 (positions of nonzero terms).

Programs

  • PARI
    A007949(n) = valuation(n,3);
    A156552(n) = { my(f = factor(n), p2 = 1, res = 0); for(i = 1, #f~, p = 1 << (primepi(f[i, 1]) - 1); res += (p * p2 * (2^(f[i, 2]) - 1)); p2 <<= f[i, 2]); res };
    A341354(n) = A007949(A156552(2*n));

Formula

a(n) = A341353(2*n) = A007949(A156552(2*n)) = A007949(1+(2*A156552(n))).
For all n >= 1, a(A000040(2*n)) = a(n^2) = 0.

A353277 Lexicographically earliest infinite sequence such that a(i) = a(j) => f(i) = f(j), where f(n) = [A020639(n), A341353(n)], with f(1) = 1.

Original entry on oeis.org

1, 2, 3, 4, 5, 2, 6, 2, 7, 8, 9, 2, 10, 2, 3, 4, 11, 2, 12, 2, 13, 4, 14, 2, 15, 2, 3, 2, 16, 4, 17, 2, 3, 4, 5, 18, 19, 2, 7, 4, 20, 2, 21, 2, 3, 18, 22, 2, 23, 2, 3, 2, 24, 2, 25, 2, 7, 2, 26, 2, 27, 4, 3, 8, 5, 4, 28, 2, 3, 2, 29, 2, 30, 2, 3, 2, 6, 2, 31, 2, 7, 4, 32, 4, 15, 2, 33, 18, 34, 8, 35, 2, 3, 8, 5, 2
Offset: 1

Views

Author

Antti Karttunen, Apr 10 2022

Keywords

Comments

Restricted growth sequence transform of function f(1) = 1, and for n > 1, f(n) = [A007814(u), A007949(u)], where u = A156552(n).

Crossrefs

Cf. A007814, A007949, A020639, A156552, A341353, A353278 (ordinal transform).
Cf. also A322026, A340680, A341355.

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; };
    A007814(n) = valuation(n,2);
    A007949(n) = valuation(n,3);
    A156552(n) = { my(f = factor(n), p, p2 = 1, res = 0); for(i = 1, #f~, p = 1 << (primepi(f[i, 1]) - 1); res += (p * p2 * (2^(f[i, 2]) - 1)); p2 <<= f[i, 2]); res };
    Aux353277(n) = if(1==n,1,my(u=A156552(n)); [A007814(u), A007949(u)]);
    v353277 = rgs_transform(vector(up_to, n, Aux353277(n)));
    A353277(n) = v353277[n];
Showing 1-3 of 3 results.