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.

Previous Showing 11-13 of 13 results.

A366913 a(n) is the least k such that A366912(k) = n.

Original entry on oeis.org

1, 2, 3, 4, 9, 10, 23, 28, 29, 84, 170, 353, 805, 850, 2171, 4860, 11815, 28025, 31539, 131252, 318231, 406904, 1612758, 2461032, 9917597, 11551434, 36824781, 80492173, 206009383, 505512671, 1361256869, 2467754261
Offset: 0

Views

Author

Rémy Sigrist, Oct 27 2023

Keywords

Comments

a(n) corresponds to the index of the first term of A364054 with height n.

Links

Crossrefs

Cf. A064290, A364054, A366912.

Programs

  • PARI
    See Links section.
(C++) See Links section.
  • Python
    from itertools import count
from sympy import nextprime
def A366913(n):
    a, aset, p, c = 1, {0,1}, 2, 0
    for i in count(1):
        if c == n:
            return i
        k, b = divmod(a,p)
        for j in count(-k):
            if b not in aset:
                aset.add(b)
                a, p = b, nextprime(p)
                c += j
                break
            b += p # Chai Wah Wu, Oct 27 2023

Extensions

a(29) from Chai Wah Wu, Oct 27 2023
a(30)-a(31) from Chai Wah Wu, Oct 28 2023

A366868 a(n) = A366470(A366864(n)-1).

Original entry on oeis.org

0, 1, 0, 1, 6, 1, 6, 15, 24, 29, 22, 1, 0, 7, 6, 11, 48, 109, 0, 7, 66, 155, 54, 21, 16, 11
Offset: 1

Views

Author

Chai Wah Wu, Oct 25 2023

Keywords

Comments

Terms of A366470 at the end of a segment. Some values, e.g. 0, 1, 6, 7, 11, occur multiple times. Will they occur infinitely often?

Crossrefs

Cf. A364054, A366470, A366864, A366869.

Programs

  • Python
    from itertools import count, islice
from sympy import nextprime
def A366868_gen(): # generator of terms
    a, aset, p = 1, {0,1}, 2
    for i in count(3):
        for b in count(a,p):
            if b not in aset:
                aset.add(b)
                c = b%(p:=nextprime(p))
                if c > a:
                    yield a
                a = c
                break
A366868_list = list(islice(A366868_gen(),20))

A366869 a(n) = A366470(A366864(n)).

Original entry on oeis.org

1, 4, 15, 26, 81, 158, 417, 990, 2491, 6402, 17363, 44450, 119773, 326786, 659957, 1845500, 4779649, 9921002, 27575339, 67458614, 187615521, 515594444, 1433794185, 3989181038, 11160791967, 31287537756
Offset: 1

Views

Author

Chai Wah Wu, Oct 25 2023

Keywords

Comments

Terms of A366470 at the beginning of a segment (except for the first segment).

Crossrefs

Cf. A364054, A366470, A366864, A366868.

Programs

  • Python
    from itertools import count, islice
from sympy import nextprime
def A366869_gen(): # generator of terms
    a, aset, p = 1, {0,1}, 2
    for i in count(3):
        for b in count(a,p):
            if b not in aset:
                aset.add(b)
                c = b%(p:=nextprime(p))
                if c > a:
                    yield c
                a = c
                break
A366869_list = list(islice(A366869_gen(), 20))
Previous Showing 11-13 of 13 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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