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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A277017 Number of maximal runs of 1-bits (in binary expansion of n) such that the length of run >= A000040(1 + the total number of zeros to the right of that run).

Original entry on oeis.org

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

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Author

Antti Karttunen, Sep 26 2016

Keywords

Comments

a(n) = number of 1-runs in binary expansion of n that exceed the length allotted to that run by primorial base coding used in A277022. If a(n) = 0, then n is in the range of A277022.

Examples

			For n=3, "11" in binary, the only maximal run of 1-bits is of length 2, and 2 >= prime(0+1) (where 0 is the total number of zeros to the right of it), thus a(3) = 1.
For n=59, "111011" in binary, both the length of run "11" at the least significant end exceeds the limit (see case n=3 above), and also the length of run "111" >= prime(1 + the total number of 0's to the right of it) = prime(2) = 3, thus a(59) = 1+1 = 2.
For n=60, "111100" in binary, the length of only run of 1's is 4, and 4 < prime(2+1) = 5, thus a(60) = 0.
		

Crossrefs

Cf. A277018 (positions of zeros), A277019 (of nonzeros).
Differs from similar A277007 for the first time at n=60, where a(60)=0, while A277007(60)=1.

Programs

  • Scheme
    (define (A277017 n) (let loop ((e 0) (n n) (z 0) (r 0)) (cond ((zero? n) (+ e (if (>= r (A000040 (+ 1 z))) 1 0))) ((even? n) (loop (+ e (if (>= r (A000040 (+ 1 z))) 1 0)) (/ n 2) (+ 1 z) 0)) (else (loop e (/ (- n 1) 2) z (+ 1 r))))))

Formula

a(n) = A129251(A005940(1+n)).

A277018 Numbers n for which A277017(n) = 0; range of A277022 sorted into ascending order.

Original entry on oeis.org

0, 1, 2, 4, 5, 6, 8, 9, 10, 12, 13, 16, 17, 18, 20, 21, 22, 24, 25, 26, 28, 32, 33, 34, 36, 37, 38, 40, 41, 42, 44, 45, 48, 49, 50, 52, 53, 54, 56, 57, 58, 60, 64, 65, 66, 68, 69, 70, 72, 73, 74, 76, 77, 80, 81, 82, 84, 85, 86, 88, 89, 90, 92, 96, 97, 98, 100, 101, 102, 104, 105, 106, 108, 109, 112, 113, 114, 116, 117, 118, 120
Offset: 0

Views

Author

Antti Karttunen, Sep 26 2016

Keywords

Comments

Numbers such that no run of 1-bits has length >= A000040(1 + the total number of 0-bits anywhere right of that run in the binary expansion of n).
Indexing starts from zero as a(0) = 0 is a special case in this sequence.

Examples

			60 ("111100" in binary, A007088) is present as 4 < prime(2+1) = 5.
		

Crossrefs

Complement: A277019.
Positions of zeros in A277017.
Sequence A277022 sorted into ascending order.
Differs from its subsequence of A277008 for the first time at n=41, where a(41)=60, a value which is missing from A277008.

Formula

Other identitities:
A129251(A005940(1+a(n))) = 0 for all n.

A277009 Numbers not in range of A277012: numbers such that at least one run of 1-bits in their binary expansion is longer than 1 + the total number of 0-bits anywhere right of that run.

Original entry on oeis.org

3, 7, 11, 14, 15, 19, 23, 27, 29, 30, 31, 35, 39, 43, 46, 47, 51, 55, 59, 60, 61, 62, 63, 67, 71, 75, 78, 79, 83, 87, 91, 93, 94, 95, 99, 103, 107, 110, 111, 115, 119, 121, 122, 123, 124, 125, 126, 127, 131, 135, 139, 142, 143, 147, 151, 155, 157, 158, 159, 163, 167, 171, 174, 175, 179, 183, 187, 188, 189, 190, 191, 195, 199, 203
Offset: 1

Views

Author

Antti Karttunen, Sep 25 2016

Keywords

Comments

Numbers n for which A277007(n) > 0.
Numbers n for which A276077(A005940(1+n)) > 0.

Examples

			3 ("11" in binary, A007088) is present as the length of that only run of 1's is 2, and 2 > 1+0, where 0 is the total number of 0's to the right of that run.
60 ("111100" in binary) is present as 4 > 2+1.
246 ("11110110" in binary) is present as the length of the leftmost run of 1-bits is 4, and 4 > 1+2, where 2 is the total number of 0's located anywhere to the right of that run.
		

Crossrefs

Complement: A277008.
Positions of nonzeros in A277007. Numbers not present in A277012.
Differs from its subsequence A277019 for the first time at n=20, where a(20)=60, a term not present in A277019.
Showing 1-3 of 3 results.