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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A246677 Permutation of natural numbers: a(1) = 1, a(2n) = A000079(A055396(2n+1)-1) * ((2*A246277(2n+1))-1), a(2n+1) = 1 + 2*a(n).

Original entry on oeis.org

1, 2, 3, 4, 5, 8, 7, 6, 9, 16, 11, 32, 17, 10, 15, 64, 13, 128, 19, 18, 33, 256, 23, 12, 65, 14, 35, 512, 21, 1024, 31, 26, 129, 20, 27, 2048, 257, 42, 39, 4096, 37, 8192, 67, 22, 513, 16384, 47, 24, 25, 50, 131, 32768, 29, 36, 71, 66, 1025, 65536, 43, 131072, 2049, 38, 63, 52, 53, 262144, 259, 74, 41
Offset: 1

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Author

Antti Karttunen, Sep 01 2014

Keywords

Comments

See the comments in A246675. This is otherwise similar permutation, except for odd numbers, which are here recursively permuted by the emerging permutation itself. The even bisection halved gives A246679, the odd bisection from a(3) onward with one subtracted and then halved gives this sequence back.

Crossrefs

Inverse: A246678. Variants: A246675, A246683.
Even bisection halved: A246679.
a(n) differs from A156552(n+1) for the first time at n=32, where a(32) = 26, while A156552(33) = 34.

Formula

a(1) = 1, a(2n) = A000079(A055396(2n+1)-1) * ((2*A246277(2n+1))-1), a(2n+1) = 1 + 2*a(n).

A250247 Permutation of natural numbers: a(1) = 1, a(n) = A083221(a(A055396(n)),A246277(n)).

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, 27, 22, 23, 24, 25, 26, 21, 28, 29, 30, 31, 32, 39, 34, 35, 36, 37, 38, 63, 40, 41, 42, 43, 44, 33, 46, 47, 48, 49, 50, 75, 52, 53, 54, 65, 56, 99, 58, 59, 60, 61, 62, 57, 64, 95, 66, 67, 68, 111, 70, 71, 72, 103, 74, 51, 76, 77, 78, 79, 80, 45, 82
Offset: 1

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Author

Antti Karttunen, Nov 17 2014

Keywords

Comments

The first 7-cycle occurs at: (33 39 63 57 99 81 45), which is mirrored at the cycle (137 167 307 269 523 419 197), consisting of primes (p_33, p_39, p_63, ...).

Examples

			As a(21) = 27, and A000040(21) = 73 and A000040(27) = 103, a(73) = 103.
		

Crossrefs

Inverse: A250248.
Differs from its inverse A250248 for the first time at n = 33, where a(33) = 39, while A250248(33) = 45.
Differs from the "vanilla version" A249817 for the first time at n=73, where a(73) = 103, while A249817(73) = 73.
Differs from "doubly recursed" version A250249 for the first time at n=42, where a(42) = 42, while A250249(42) = 54, thus the first prime where they get different values is p_42 = 181, where a(181) = 181, while A250249(181) = 251 = p_54.

Formula

a(1) = 1, a(n) = A083221(a(A055396(n)),A246277(n)).
Other identities. For all n >= 1:
a(A005843(n)) = A005843(n). [Fixes even numbers].
a(p_n) = p_{a(n)}, or equally, a(n) = A049084(a(A000040(n))). [Restriction to primes induces the same sequence].
A078442(a(n)) = A078442(n), A049076(a(n)) = A049076(n). [Preserves the "order of primeness of n"].

A300247 Restricted growth sequence transform of A286457(n), filter combining A078898(n) and A246277(n).

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Mar 03 2018

Keywords

Comments

For all i, j:
a(i) = a(j) => A280492(i) = A280492(j).
a(i) = a(j) => A300248(i) = A300248(j).
The latter follows because A046523(n) = A046523(2*A246277(n)).

Examples

			a(65) = a(119) (= 42) because A078898(65) = A078898(119) = 5 (both numbers occur in column 5 of A083221) and because A246277(65) = A246277(119) = 7 (both numbers occur in column 7 of A246278). Note that 65 = 5*13 = prime(3)*prime(6) and 119 = 7*17 = prime(4)*prime(7) = A003961(65). A246277(n) contains complete information about the (relative) differences between prime indices in the prime factorization of n.
		

Crossrefs

Programs

  • PARI
    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; };
    write_to_bfile(start_offset,vec,bfilename) = { for(n=1, length(vec), write(bfilename, (n+start_offset)-1, " ", vec[n])); }
    A020639(n) = { if(1==n,n,vecmin(factor(n)[, 1])); };
    A064989(n) = {my(f); f = factor(n); if((n>1 && f[1,1]==2), f[1,2] = 0); for (i=1, #f~, f[i,1] = precprime(f[i,1]-1)); factorback(f)};
    A078898(n) = { if(n<=1,n, my(spf=A020639(n),k=1,m=n/spf); while(m>1,if(A020639(m)>=spf,k++); m--); (k)); }; \\ Antti Karttunen, Mar 03 2018
    A246277(n) = { if(1==n, 0, while((n%2), n = A064989(n)); (n/2)); };
    A286457(n) = if(1==n,0,(1/2)*(2 + ((A078898(n)+A246277(n))^2) - A078898(n) - 3*A246277(n)));
    write_to_bfile(1,rgs_transform(vector(65537,n,A286457(n))),"b300247.txt");

A249825 Permutation of natural numbers: a(n) = A246277(A084968(n)).

Original entry on oeis.org

1, 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 4, 41, 43, 47, 53, 59, 61, 6, 67, 71, 73, 10, 79, 83, 89, 97, 101, 103, 14, 9, 107, 109, 22, 113, 127, 15, 131, 137, 139, 26, 149, 151, 25, 157, 163, 167, 21, 173, 179, 181, 191, 34, 33, 193, 38, 35, 197, 199, 211, 223, 227, 229, 55, 233, 39, 239, 46, 241, 251, 257, 263, 269, 271, 58, 49
Offset: 1

Views

Author

Antti Karttunen, Dec 06 2014

Keywords

Crossrefs

Programs

Formula

a(n) = A246277(A084968(n)).
As a composition of other permutations:
a(n) = A249823(A250475(n)).
a(n) = A064216(A249745(A250475(n))). [Composition of the first three rows of array A251721.]

A329620 Lexicographically earliest infinite sequence such that a(i) = a(j) => f(i) = f(j), where f(n) = [A046523(n), A246277(A324886(n))].

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Nov 18 2019

Keywords

Comments

Restricted growth sequence transform of the ordered pair [A046523(n), A246277(A324886(n))].
For all i, j:
A305800(i) = A305800(j) => a(i) = a(j),
a(i) = a(j) => A101296(i) = A101296(j),
a(i) = a(j) => A329345(i) = A329345(j),
a(i) = a(j) => A329618(i) = A329618(j),
a(i) = a(j) => A329619(i) = A329619(j).

Crossrefs

Programs

  • PARI
    up_to = 8192;
    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; };
    A046523(n) = { my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]); }; \\ From A046523
    A034386(n) = prod(i=1, primepi(n), prime(i));
    A108951(n) = { my(f=factor(n)); prod(i=1, #f~, A034386(f[i, 1])^f[i, 2]) };  \\ From A108951
    A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
    A324886(n) = A276086(A108951(n));
    A246277(n) = if(1==n, 0, my(f = factor(n), k = primepi(f[1,1])-1); for (i=1, #f~, f[i,1] = prime(primepi(f[i,1])-k)); factorback(f)/2);
    Aux329620(n) = [A046523(n), A246277(A324886(n))];
    v329620 = rgs_transform(vector(up_to, n, Aux329620(n)));
    A329620(n) = v329620[n];

A280492 a(1) = 0; for n > 1, a(n) = A246277(n) - A078898(n).

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, 4, 0, 0, 0, 1, 0, 7, 0, 0, 0, 0, 0, -1, 0, 2, 0, 0, 0, 7, 0, 0, 0, 0, 0, -4, 0, 0, 0, 0, 0, -6, 0, 0, 0, 5, 0, 8, 0, 0, 0, 1, 0, 13, 0, 6, 0, 0, 0, -3, 0, 0, 0, 0, 0, -3, 0, 0, 0, 0, 0, 12, 0, 0, 0, 9, 0, 2, 0, 2
Offset: 1

Views

Author

Antti Karttunen, Jan 09 2017

Keywords

Comments

For n > 1, a(n) gives the difference of column positions of n's location in arrays A246278 and A083221. Note that any n occurs on the same row in both arrays.

Crossrefs

Programs

Formula

a(1) = 0; for n > 1, a(n) = A246277(n) - A078898(n).

A304728 Restricted growth sequence transform of A246277(A303751(n)).

Original entry on oeis.org

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

Views

Author

Antti Karttunen, May 19 2018

Keywords

Comments

For all i, j: a(i) = a(j) => A304729(i) = A304729(j).

Crossrefs

Programs

  • PARI
    A064989(n) = {my(f); f = factor(n); if((n>1 && f[1,1]==2), f[1,2] = 0); for (i=1, #f~, f[i,1] = precprime(f[i,1]-1)); factorback(f)};
    A246277(n) = { if(1==n, 0, while((n%2), n = A064989(n)); (n/2)); };
    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; };
    v304728 = rgs_transform(vector(76503,n,A246277(A303751(n)))); \\ Needs also code from A303751
    A304728(n) = v304728[n];

A305796 Dirichlet convolution of A246277 with itself.

Original entry on oeis.org

0, 0, 0, 1, 0, 2, 0, 4, 1, 2, 0, 10, 0, 2, 2, 12, 0, 10, 0, 14, 2, 2, 0, 32, 1, 2, 4, 18, 0, 22, 0, 32, 2, 2, 2, 47, 0, 2, 2, 48, 0, 30, 0, 26, 10, 2, 0, 88, 1, 14, 2, 30, 0, 38, 2, 64, 2, 2, 0, 104, 0, 2, 14, 80, 2, 42, 0, 38, 2, 30, 0, 148, 0, 2, 10, 42, 2, 54, 0, 136, 12, 2, 0, 144, 2, 2, 2, 96, 0, 98, 2, 50, 2, 2, 2, 224, 0, 18, 18, 103, 0, 66, 0, 112, 22
Offset: 1

Views

Author

Antti Karttunen, Jun 13 2018

Keywords

Crossrefs

Programs

  • PARI
    A064989(n) = {my(f); f = factor(n); if((n>1 && f[1,1]==2), f[1,2] = 0); for (i=1, #f~, f[i,1] = precprime(f[i,1]-1)); factorback(f)};
    A246277(n) = { if(1==n, 0, while((n%2), n = A064989(n)); (n/2)); };
    A305796(n) = sumdiv(n,d,A246277(d)*A246277(n/d));

Formula

a(n) = Sum_{d|n} A246277(d)*A246277(n/d).

A329038 a(n) = A246277(A276086(n)).

Original entry on oeis.org

0, 1, 1, 3, 2, 9, 1, 5, 3, 15, 6, 45, 2, 25, 9, 75, 18, 225, 4, 125, 27, 375, 54, 1125, 8, 625, 81, 1875, 162, 5625, 1, 7, 5, 21, 10, 63, 3, 35, 15, 105, 30, 315, 6, 175, 45, 525, 90, 1575, 12, 875, 135, 2625, 270, 7875, 24, 4375, 405, 13125, 810, 39375, 2, 49, 25, 147, 50, 441, 9, 245, 75, 735, 150, 2205, 18, 1225, 225, 3675, 450, 11025, 36
Offset: 0

Views

Author

Antti Karttunen, Nov 08 2019

Keywords

Crossrefs

Cf. A046523, A246277, A276086, A278226, A329048 (rgs-transform).
Cf. also A329345.

Programs

  • PARI
    A246277(n) = if(1==n, 0, my(f = factor(n), k = primepi(f[1,1])-1); for (i=1, #f~, f[i,1] = prime(primepi(f[i,1])-k)); factorback(f)/2);
    A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
    A329038(n) = A246277(A276086(n));

Formula

a(n) = A246277(A276086(n)).
For n >= 1, A046523(2*a(n)) = A278226(n).

A342457 Terms of A342456 prime-shifted so far towards lower primes that they become even: a(n) = 2*A246277(A342456(n)).

Original entry on oeis.org

2, 2, 2, 4, 2, 4, 6, 6, 2, 4, 64, 16, 324, 36, 10, 36, 2, 4, 64, 16, 2304, 96, 486, 24, 7290, 104976, 21600, 1296, 1708593750000, 100, 93750, 10, 2, 4, 64, 16, 144, 6, 216, 6, 172186884, 7776, 2160, 216, 216000000, 236196, 10497600, 54, 10935000000000, 53144100, 1476225000000, 7290, 122500000000, 10935000, 140, 360
Offset: 0

Views

Author

Antti Karttunen, Mar 15 2021

Keywords

Comments

These terms have the same prime signature as the corresponding terms in A342456, thus applying omega and bigomega to these gives the same derived sequences A342461 and A342462.

Crossrefs

Programs

  • PARI
    A246277(n) = if(1==n, 0, my(f = factor(n), k = primepi(f[1,1])-1); for (i=1, #f~, f[i,1] = prime(primepi(f[i,1])-k)); factorback(f)/2);
    A342457(n) = 2*A246277(A342456(n)); \\ Uses also code from A342456.

Formula

a(n) = 2*A246277(A342456(n)) = 2*A329038(A329886(n)).
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