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 1-4 of 4 results.

A336120 a(n) = A292383(A122111(n)).

Original entry on oeis.org

0, 0, 0, 1, 0, 2, 0, 2, 0, 4, 0, 4, 0, 8, 0, 5, 0, 5, 0, 8, 0, 16, 0, 10, 1, 32, 0, 16, 0, 10, 0, 11, 0, 64, 2, 8, 0, 128, 0, 20, 0, 20, 0, 32, 0, 256, 0, 22, 0, 8, 0, 64, 0, 11, 4, 40, 0, 512, 0, 16, 0, 1024, 0, 22, 8, 40, 0, 128, 0, 16, 0, 20, 0, 2048, 1, 256, 0, 80, 0, 44, 0, 4096, 0, 32, 16, 8192, 0, 80, 0, 22, 0, 512, 0, 16384, 32, 44, 0, 17, 0, 17, 0
Offset: 1

Views

Author

Antti Karttunen, Jul 14 2020

Keywords

Crossrefs

Programs

  • PARI
    \\ Uses also code given in A336124:
    A253553(n) = if(n<=2,1,my(f=factor(n), k=#f~); if(f[k,2]>1,f[k,2]--,f[k,1] = precprime(f[k,1]-1)); factorback(f));
    A336120(n) = if(1==n,0,(3==A336124(n))+(2*A336120(A253553(n))));

Formula

a(1) = 0, and for n > 1, a(n) = [A122111(n) == 3 (mod 4)] + 2*a(A253553(n)).
a(n) = A292383(A122111(n)).
a(n) = A253566(n) - A336125(n).
A000120(a(n)) = A336121(n).

A336119 Numbers k such that A122111(k) [the conjugated prime factorization of k] is a square or twice a square.

Original entry on oeis.org

1, 2, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 27, 29, 31, 33, 37, 39, 41, 43, 45, 47, 49, 51, 53, 57, 59, 61, 63, 67, 69, 71, 73, 77, 79, 81, 83, 87, 89, 91, 93, 97, 99, 101, 103, 107, 109, 111, 113, 117, 119, 123, 127, 129, 131, 133, 135, 137, 139, 141, 147, 149, 151, 153, 157, 159, 161, 163, 167, 169, 171, 173
Offset: 1

Views

Author

Antti Karttunen, Jul 14 2020

Keywords

Comments

Sequence A122111(A028982(k)), k >= 1, sorted into ascending order.

Crossrefs

Cf. A000040, A066207 (subsequences), A335909 (characteristic function).
Positions of odd terms in A323173, positions of zeros in A336120 and A336121, positions of ones in A336312.

Programs

A336312 Lexicographically earliest infinite sequence such that a(i) = a(j) => A278222(A336120(i)) = A278222(A336120(j)) for all i, j >= 1.

Original entry on oeis.org

1, 1, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 3, 1, 3, 1, 2, 1, 2, 1, 3, 2, 2, 1, 2, 1, 3, 1, 4, 1, 2, 2, 2, 1, 2, 1, 3, 1, 3, 1, 2, 1, 2, 1, 4, 1, 2, 1, 2, 1, 4, 2, 3, 1, 2, 1, 2, 1, 2, 1, 4, 2, 3, 1, 2, 1, 2, 1, 3, 1, 2, 2, 2, 1, 3, 1, 4, 1, 2, 1, 2, 2, 2, 1, 3, 1, 4, 1, 2, 1, 2, 2, 4, 1, 3, 1, 3, 1, 3, 1, 3, 2
Offset: 1

Views

Author

Antti Karttunen, Jul 17 2020

Keywords

Comments

Restricted growth sequence transform of A278222(A336120(n)).
For all i, j:
a(i) = a(j) => A336121(i) = A336121(j) => A335909(i) = A335909(j).

Crossrefs

Cf. A336119 (positions of ones).

Programs

  • PARI
    up_to = 1024; \\ 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; };
    \\ Needs also code from A336124:
    A253553(n) = if(n<=2,1,my(f=factor(n), k=#f~); if(f[k,2]>1,f[k,2]--,f[k,1] = precprime(f[k,1]-1)); factorback(f));
    A336120(n) = if(1==n,0,(3==A336124(n))+(2*A336120(A253553(n))));
    A005940(n) = { my(p=2, t=1); n--; until(!n\=2, if((n%2), (t*=p), p=nextprime(p+1))); t }; \\ From A005940
    A046523(n) = { my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]); };  \\ From A046523
    A278222(n) = A046523(A005940(1+n));
    v336312 = rgs_transform(vector(up_to,n,A278222(A336120(n))));
    A336312(n) = v336312[n];

A336123 a(1) = 0, a(2) = 1, and for n > 2, a(n) = [A122111(n) == 1 (mod 4)] + a(A253553(n)).

Original entry on oeis.org

0, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 2, 1, 1, 2, 2, 1, 1, 1, 2, 2, 1, 1, 2, 1, 1, 3, 2, 1, 1, 1, 2, 2, 1, 1, 3, 1, 1, 2, 2, 1, 1, 1, 2, 3, 1, 1, 2, 2, 2, 2, 2, 1, 1, 1, 2, 2, 1, 1, 3, 1, 1, 3, 3, 1, 1, 1, 2, 2, 2, 1, 3, 1, 1, 2, 2, 2, 1, 1, 2, 4, 1, 1, 3, 1, 1, 2, 2, 1, 1, 2, 2, 2, 1, 1, 3, 1, 1, 3, 2, 1, 1, 1, 2, 2
Offset: 1

Views

Author

Antti Karttunen, Jul 17 2020

Keywords

Crossrefs

Programs

  • PARI
    \\ Uses also code given in A336124:
    A253553(n) = if(n<=2,1,my(f=factor(n), k=#f~); if(f[k,2]>1,f[k,2]--,f[k,1] = precprime(f[k,1]-1)); factorback(f));
    A336123(n) = if(n<=2,n-1,(1==A336124(n))+A336123(A253553(n)));

Formula

a(1) = 0, a(2) = 1, and for n > 2, a(n) = [A336124(n) == 1] + a(A253553(n)).
a(n) = A000120(A336125(n)).
For n > 1, a(n) = A292375(A122111(n)).
a(n) = A001222(n) - A336121(n).
For all n >= 0, a(3^n) = n.
Showing 1-4 of 4 results.