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 1-5 of 5 results.

A323369 Lexicographically earliest such sequence a that for all i, j, a(i) = a(j) => f(i) = f(j), where f(n) = 0 for odd primes, and f(n) = A323368(n) for any other number.

Original entry on oeis.org

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

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Author

Antti Karttunen, Jan 12 2019

Keywords

Comments

Restricted growth sequence transform of function f, where f(n) = 0 for odd primes, and for any other number, f(n) = [A000035(n), A003557(n), A048250(n)].
For all i, j:
A305801(i) = A305801(j) => a(i) = a(j),
a(i) = a(j) => A007814(i) = A007814(j),
a(i) = a(j) => A322588(i) = A322588(j),
a(i) = a(j) => A323238(i) = A323238(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; };
    A003557(n) = { my(f=factor(n)); for(i=1, #f~, f[i, 2] = f[i, 2]-1); factorback(f); };
    A048250(n) = factorback(apply(p -> p+1,factor(n)[,1]));
    Aux323369(n) = if((n>2)&&isprime(n),0,[(n%2), A003557(n), A048250(n)]);
    v323369 = rgs_transform(vector(up_to, n, Aux323369(n)));
    A323369(n) = v323369[n];

A295300 Lexicographically earliest sequence such that a(i) = a(j) => f(i) = f(j), where f(n) = [A003557(n), A046523(n), A048250(n)].

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 32, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 44, 49, 50, 51, 44, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 58, 62, 65, 66, 67, 68, 69, 70, 58, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 80
Offset: 1

Views

Author

Antti Karttunen, Nov 19 2017

Keywords

Comments

Restricted growth sequence transform of A291752.
For all i, j:
a(i) = a(j) => A291751(i) = A291751(j),
a(i) = a(j) => A326199(i) = A326199(j) => A294877(i) = A294877(j),
a(i) = a(j) => A322021(i) = A322021(j),
a(i) = a(j) => A295888(i) = A295888(j),
a(i) = a(j) => A296090(i) = A296090(j).

Crossrefs

Programs

  • PARI
    up_to = 100000;
    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; };
    A003557(n) = n/factorback(factor(n)[, 1]); \\ From A003557
    A046523(n) = { my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]); };  \\ From A046523
    A048250(n) = if(n<1, 0, sumdiv(n, d, if(core(d)==d, d)));
    A291750(n) = (1/2)*(2 + ((A003557(n)+A048250(n))^2) - A003557(n) - 3*A048250(n));
    Aux295300(n) = (1/2)*(2 + ((A046523(n) + A291750(n))^2) - A046523(n) - 3*A291750(n));
    v295300 = rgs_transform(vector(up_to,n,Aux295300(n)));
    A295300(n) = v295300[n];

Extensions

Name changed and the comments section added by Antti Karttunen, Jul 13 2019

A322809 Lexicographically earliest such sequence a that a(i) = a(j) => f(i) = f(j) for all i, j, where f(n) = -1 if n is an odd prime, and f(n) = floor(n/2) for all other numbers.

Original entry on oeis.org

1, 2, 3, 4, 3, 5, 3, 6, 6, 7, 3, 8, 3, 9, 9, 10, 3, 11, 3, 12, 12, 13, 3, 14, 14, 15, 15, 16, 3, 17, 3, 18, 18, 19, 19, 20, 3, 21, 21, 22, 3, 23, 3, 24, 24, 25, 3, 26, 26, 27, 27, 28, 3, 29, 29, 30, 30, 31, 3, 32, 3, 33, 33, 34, 34, 35, 3, 36, 36, 37, 3, 38, 3, 39, 39, 40, 40, 41, 3, 42, 42, 43, 3, 44, 44, 45, 45, 46, 3, 47, 47, 48, 48, 49, 49, 50, 3, 51, 51, 52, 3, 53, 3, 54, 54
Offset: 1

Views

Author

Antti Karttunen, Dec 26 2018

Keywords

Comments

This sequence is a restricted growth sequence transform of a function f which is defined as f(n) = A004526(n), unless n is an odd prime, in which case f(n) = -1, which is a constant not in range of A004526. See the Crossrefs section for a list of similar sequences.
For all i, j:
A305801(i) = A305801(j) => a(i) = a(j),
a(i) = a(j) => A039636(i) = A039636(j).
For all i, j: a(i) = a(j) <=> A323161(i+1) = A323161(j+1).
The shifted version of this filter, A323161, has a remarkable ability to find many sequences related to primes and prime chains. - Antti Karttunen, Jan 06 2019

Crossrefs

A list of few similarly constructed sequences follows, where each sequence is an rgs-transform of such function f, for which the value of f(n) is the n-th term of the sequence whose A-number follows after a parenthesis, unless n is of the form ..., in which case f(n) is given a constant value outside of the range of that sequence:
A322809 (A004526, unless an odd prime) [This sequence],
A322589 (A007913, unless an odd prime),
A322591 (A007947, unless an odd prime),
A322805 (A252463, unless an odd prime),
A323082 (A300840, unless an odd prime),
A322822 (A300840, unless n > 2 and a Fermi-Dirac prime, A050376),
A322988 (A322990, unless a prime power > 2),
A323078 (A097246, unless an odd prime),
A322808 (A097246, unless a squarefree number > 2),
A322816 (A048675, unless an odd prime),
A322807 (A285330, unless an odd prime),
A322814 (A286621, unless an odd prime),
A322824 (A242424, unless an odd prime),
A322973 (A006370, unless an odd prime),
A322974 (A049820, unless n > 1 and n is in A046642),
A323079 (A060681, unless an odd prime),
A322587 (A295887, unless an odd prime),
A322588 (A291751, unless an odd prime),
A322592 (A289625, unless an odd prime),
A323369 (A323368, unless an odd prime),
A323371 (A295886, unless an odd prime),
A323374 (A323373, unless an odd prime),
A323401 (A323372, unless an odd prime),
A323405 (A323404, unless an odd prime).

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; };
    A322809aux(n) = if((n>2)&&isprime(n),-1,(n>>1));
    v322809 = rgs_transform(vector(up_to,n,A322809aux(n)));
    A322809(n) = v322809[n];

Formula

a(n) = A323161(n+1) - 1.

A323366 Lexicographically earliest sequence such that for all i, j, a(i) = a(j) => A000035(i) = A000035(j) and A003557(i) = A003557(j) and A173557(i) = A173557(j).

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 13, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 34, 38, 39, 25, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 39, 52, 36, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 56, 65, 72, 73, 74, 75, 76, 49, 77, 78, 79, 80, 81, 82, 68, 83, 56, 84, 68, 85, 86, 87, 88, 89, 90, 91, 92, 93, 60
Offset: 1

Views

Author

Antti Karttunen, Jan 12 2019

Keywords

Comments

For all i, j:
a(i) = a(j) => A007814(i) = A007814(j),
a(i) = a(j) => A295887(i) = A295887(j),
a(i) = a(j) => A323237(i) = A323237(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; };
    A003557(n) = { my(f=factor(n)); for(i=1, #f~, f[i, 2] = f[i, 2]-1); factorback(f); };
    A173557(n) = my(f=factor(n)[, 1]); prod(k=1, #f, f[k]-1); \\ From A173557
    v323366 = rgs_transform(vector(up_to, n, [(n%2), A003557(n), A173557(n)]));
    A323366(n) = v323366[n];

A369259 Lexicographically earliest infinite sequence such that a(i) = a(j) => A003557(i) = A003557(j), A048250(i) = A048250(j) and A342671(i) = A342671(j), for all i, j >= 1.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Jan 25 2024

Keywords

Comments

Restricted growth sequence transform of the triplet [A003557(j), A048250(i), A342671(n)].
For all i, j >= 1:
a(i) = a(j) => A323368(i) = A323368(j) => A291751(i) = A291751(j),
a(i) = a(j) => A369260(i) = A369260(j) => A286603(i) = A286603(j).

Crossrefs

Differs from related A296089 and A323368 for the first time at n=79, where a(79) = 69, while A296089(79) = A323368(79) = 51.

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; };
    A003557(n) = (n/factorback(factor(n)[, 1]));
    A003961(n) = { my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); };
    A048250(n) = if(n<1, 0, sumdiv(n, d, if(core(d)==d, d)));
    A342671(n) = gcd(sigma(n), A003961(n));
    Aux369259(n) = [A003557(n), A048250(n), A342671(n)];
    v369259 = rgs_transform(vector(up_to, n, Aux369259(n)));
    A369259(n) = v369259[n];
Showing 1-5 of 5 results.