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.

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A324874 a(n) is the binary length of A324398(n), where A324398(n) = A156552(n) AND (A323243(n) - A156552(n)).

Original entry on oeis.org

0, 0, 0, 1, 0, 1, 0, 1, 3, 0, 0, 1, 0, 1, 4, 4, 0, 1, 0, 1, 5, 1, 0, 1, 0, 1, 4, 1, 0, 1, 0, 1, 0, 1, 5, 4, 0, 1, 7, 1, 0, 1, 0, 1, 3, 1, 0, 1, 0, 0, 2, 1, 0, 1, 6, 1, 9, 1, 0, 1, 0, 1, 3, 6, 0, 1, 0, 1, 0, 1, 0, 5, 0, 1, 5, 1, 6, 1, 0, 1, 4, 1, 0, 1, 8, 1, 11, 1, 0, 6, 7, 1, 0, 1, 9, 5, 0, 0, 7, 5, 0, 1, 0, 1, 6
Offset: 1

Views

Author

Antti Karttunen, Mar 27 2019

Keywords

Crossrefs

Programs

  • PARI
    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}; \\ From A156552
    A324398(n) = { my(k=A156552(n)); bitand(k,(A323243(n)-k)); }; \\ Needs also code from A323243.
    A324874(n) = #binary(A324398(n));

Formula

If A324398(n) = 0, a(n) = 0, otherwise a(n) = A070939(A324398(n)) = 1 + A000523(A324398(n)).
a(n) = A324868(n) + A324881(n).
a(p) = 0 for all primes p.

A324865 a(n) = A323243(n) - A156552(n).

Original entry on oeis.org

0, 0, 1, 1, 3, 1, 7, 1, 6, 4, 15, 1, 31, 1, 8, 9, 63, 1, 127, 1, 21, 15, 255, 1, 16, 19, 10, 13, 511, 11, 1023, 1, 20, 47, 22, 13, 2047, 1, 78, 17, 4095, 1, 8191, 1, 14, 287, 16383, 1, 36, 6, 122, 1, 32767, 1, 55, 1, 270, 277, 65535, 1, 131071, 687, 22, 41, 58, 27, 262143, 45, 260, 1, 524287, 17, 1048575, 259, 16
Offset: 1

Views

Author

Antti Karttunen, Mar 18 2019

Keywords

Crossrefs

Programs

Formula

a(1) = 0; for n > 1, a(n) = A001065(A156552(n)).
a(n) = A323243(n) - A156552(n).

A324879 Numbers k such that A324863(k) is equal to A324874(k).

Original entry on oeis.org

1, 9, 15, 16, 21, 27, 35, 39, 55, 57, 64, 75, 77, 85, 87, 90, 91, 95, 99, 105, 111, 115, 119, 125, 129, 133, 143, 147, 155, 159, 161, 175, 183, 185, 189, 195, 201, 203, 205, 209, 213, 221, 235, 237, 243, 245, 253, 256, 259, 265, 267, 275, 285, 287, 295, 299, 301, 303, 319, 321, 323, 325, 335, 339, 341, 351, 355, 363, 365
Offset: 1

Views

Author

Antti Karttunen, Mar 27 2019

Keywords

Comments

In range 1..10000, there are only three such numbers k for which A324868(k) == A000120(A324866(k)): 1, 9, 125. See A324201.

Crossrefs

Subsequences: A324201, A324880 (even terms).

Programs

A324881 Number of nonleading zeros in binary representation of A324398, where A324398(n) = A156552(n) AND (A323243(n) - A156552(n)).

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 3, 2, 0, 0, 0, 0, 4, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 3, 2, 0, 0, 5, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 4, 0, 7, 0, 0, 0, 0, 0, 1, 3, 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 4, 0, 5, 0, 0, 0, 2, 0, 0, 0, 6, 0, 9, 0, 0, 4, 5, 0, 0, 0, 8, 2, 0, 0, 5, 3, 0, 0, 0, 0, 4
Offset: 1

Views

Author

Antti Karttunen, Mar 27 2019

Keywords

Examples

			For n=4, A324398(4) = 1, in binary "1", thus a(4) = 0.
For n=9, A324398(9) = 6, in binary "110", thus a(9) = 1.
For n=16, A324398(16) = 9, in binary "1001", thus a(16) = 2.
		

Crossrefs

Programs

Formula

a(n) = A080791(A324398(n)) = A324874(n) - A324868(n).
a(p) = 0 for all primes p.
Showing 1-4 of 4 results.