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 11-20 of 20 results.

A342651 a(n) = A329697(A156552(n)).

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Mar 18 2021

Keywords

Crossrefs

Cf. A000040 (positions of 0's), A350069 (of 1's).

Programs

  • PARI
    A156552(n) = {my(f = factor(n), p, p2 = 1, res = 0); for(i = 1, #f~, p = 1 << (primepi(f[i, 1]) - 1); res += (p * p2 * (2^(f[i, 2]) - 1)); p2 <<= f[i, 2]); res};
    A329697(n) = { my(f=factor(n)); sum(k=1,#f~,if(2==f[k,1],0,f[k,2]*(1+A329697(f[k,1]-1)))); };
    A342651(n) = A329697(A156552(n));
    
  • PARI
    \\ Version using the factorization file available at https://oeis.org/A156552/a156552.txt
    v156552sigs = readvec("a156552.txt");
    A329697(n) = { my(f=factor(n)); sum(k=1,#f~,if(2==f[k,1],0,f[k,2]*(1+A329697(f[k,1]-1)))); };
    A342651(n) = if(isprime(n),0,my(prsig=v156552sigs[n],ps=prsig[1],es=prsig[2]); sum(i=2-(ps[1]%2),#ps,es[i]*(1+A329697(ps[i]-1)))); \\ Antti Karttunen, Jan 29 2022

Formula

a(n) = A329697(A156552(n)) = A329697(A322993(n)).
a(n) = A329697(A342666(n)) + A342656(n).
a(p) = 0 for all primes p.
a(A003961(n)) = a(n).

A350065 Lexicographically earliest infinite sequence such that a(i) = a(j) => A350063(i) = A350063(j), for all i, j >= 1.

Original entry on oeis.org

1, 2, 2, 3, 2, 3, 2, 3, 3, 4, 2, 3, 2, 3, 3, 5, 2, 3, 2, 3, 4, 5, 2, 3, 3, 5, 3, 5, 2, 5, 2, 3, 3, 5, 3, 6, 2, 3, 5, 5, 2, 3, 2, 3, 3, 7, 2, 3, 3, 4, 5, 3, 2, 3, 4, 3, 5, 8, 2, 3, 2, 5, 3, 8, 3, 5, 2, 5, 3, 3, 2, 5, 2, 5, 3, 5, 3, 5, 2, 3, 5, 5, 2, 8, 5, 9, 7, 7, 2, 8, 4, 5, 8, 10, 5, 5, 2, 4, 5, 5, 2, 8, 2, 3, 5
Offset: 1

Views

Author

Antti Karttunen, Jan 29 2022

Keywords

Comments

Restricted growth sequence transform of A350063.
For all i, j >= 1: A305897(i) = A305897(j) => a(i) = a(j) => A324117(i) = A324117(j).
For all i, j >= 2: a(i) = a(j) => A342656(i) = A342656(j).

Crossrefs

Programs

  • PARI
    up_to = 3000;
    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; };
    A000265(n) = (n>>valuation(n,2));
    A046523(n) = { my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]); };  \\ From A046523
    A156552(n) = { my(f = factor(n), p, p2 = 1, res = 0); for(i = 1, #f~, p = 1 << (primepi(f[i, 1]) - 1); res += (p * p2 * (2^(f[i, 2]) - 1)); p2 <<= f[i, 2]); res };
    A350063(n) = if(1==n,0,A046523(A000265(A156552(n))));
    v350065 = rgs_transform(vector(up_to, n, A350063(n)));
    A350065(n) = v350065[n];
    
  • PARI
    \\ Version using the factorization file available at https://oeis.org/A156552/a156552.txt
    v156552sigs = readvec("a156552.txt");
    up_to = #v156552sigs;
    A350063(n) = if(n<=2,n-1,my(es=v156552sigs[n][2]); if(n%2, es = vector(#es-1,i,es[1+i])); my(f=vecsort(es, , 4), p=0); prod(i=1, #f, (p=nextprime(p+1))^f[i]));
    v350065 = rgs_transform(vector(up_to, n, A350063(n)));
    A350065(n) = v350065[n]; \\ Antti Karttunen, Jan 29 2022

A350067 Lexicographically earliest infinite sequence such that a(i) = a(j) => f(i) = f(j), where f(n) = [A342666(n), A350063(n)] for n > 1, with f(1) = 1.

Original entry on oeis.org

1, 2, 2, 3, 2, 3, 2, 4, 3, 5, 2, 6, 2, 3, 3, 7, 2, 4, 2, 8, 5, 9, 2, 10, 3, 11, 4, 11, 2, 11, 2, 12, 3, 13, 3, 14, 2, 3, 9, 11, 2, 8, 2, 15, 6, 16, 2, 17, 3, 5, 11, 18, 2, 19, 5, 20, 13, 21, 2, 22, 2, 23, 8, 24, 3, 25, 2, 26, 3, 6, 2, 9, 2, 27, 4, 28, 3, 26, 2, 29, 7, 30, 2, 31, 9, 32, 16, 33, 2, 31, 5, 34, 21, 35
Offset: 1

Views

Author

Antti Karttunen, Jan 29 2022

Keywords

Comments

Restricted growth sequence transform of the ordered pair [A342666(n), A350063(n)], when assuming that A342666(1) = 0.
Restricted growth sequence transform of the function f(1) = 0, f(n) = A336470(A156552(n)) for n > 1.
For all i, j >= 1: A305897(i) = A305897(j) => a(i) = a(j) => A350065(i) = A350065(j).
For all i, j >= 2: a(i) = a(j) => A342651(i) = A342651(j).

Crossrefs

Programs

  • PARI
    up_to = 3003;
    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; };
    A000265(n) = (n>>valuation(n,2));
    A003958(n) = { my(f = factor(n)); for(i=1, #f~, f[i, 1]--); factorback(f); };
    A046523(n) = { my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]); };  \\ From A046523
    A156552(n) = { my(f = factor(n), p, p2 = 1, res = 0); for(i = 1, #f~, p = 1 << (primepi(f[i, 1]) - 1); res += (p * p2 * (2^(f[i, 2]) - 1)); p2 <<= f[i, 2]); res };
    A336466(n) = { my(f=factor(n)); prod(k=1, #f~, A000265(f[k, 1]-1)^f[k, 2]); };
    Aux350067(n) = if(1==n,1,my(u=A000265(A156552(n))); [A046523(u),A336466(u)]);
    v350067 = rgs_transform(vector(up_to, n, Aux350067(n)));
    A350067(n) = v350067[n];

A322995 a(1) = 0; for n > 1, a(n) = A000265(A289271(n)).

Original entry on oeis.org

0, 1, 1, 1, 1, 3, 1, 1, 1, 5, 1, 3, 1, 9, 5, 1, 1, 17, 1, 3, 9, 33, 1, 17, 1, 65, 1, 5, 1, 7, 1, 1, 33, 129, 3, 9, 1, 257, 65, 5, 1, 11, 1, 17, 9, 513, 1, 129, 1, 1025, 257, 33, 1, 2049, 17, 3, 513, 4097, 1, 7, 1, 8193, 5, 1, 33, 19, 1, 65, 1025, 13, 1, 3, 1, 16385, 2049, 129, 9, 35, 1, 65, 1, 32769, 1, 11, 129, 65537, 4097, 5, 1, 21, 17, 257
Offset: 1

Views

Author

Antti Karttunen, Jan 02 2019

Keywords

Crossrefs

Programs

  • PARI
    A000265(n) = (n/2^valuation(n, 2));
    A289271(n) = { my(v=0,i=0,x=1); for(d=2,oo,if(n==1, return(v)); if(1==gcd(x,d)&&1==omega(d), if(!(n%d)&&1==gcd(d,n/d), v += 2^i; n /= d; x *= d); i++)); }; \\ After Rémy Sigrist's program for A289271.
    A322995(n) = if(1==n,0,A000265(A289271(n)));

Formula

a(1) = 0; for n > 1, a(n) = A000265(A289271(n)).
For all n >= 1, A000120(a(n)) = A001221(n).

A323914 Lexicographically earliest sequence such that a(i) = a(j) => A322994(i) = A322994(j), for all i, j >= 1.

Original entry on oeis.org

1, 2, 2, 3, 2, 4, 2, 5, 3, 6, 2, 5, 2, 7, 4, 8, 2, 9, 2, 8, 6, 10, 2, 8, 3, 11, 5, 12, 2, 13, 2, 12, 7, 14, 4, 8, 2, 15, 10, 12, 2, 16, 2, 17, 5, 18, 2, 12, 3, 19, 11, 20, 2, 21, 6, 17, 14, 22, 2, 8, 2, 23, 8, 17, 7, 24, 2, 25, 15, 26, 2, 12, 2, 27, 9, 28, 4, 29, 2, 17, 8, 30, 2, 12, 10, 31, 18, 20, 2, 21, 6, 32, 22, 33, 11, 17, 2, 34, 12, 12, 2, 35, 2, 25, 13
Offset: 1

Views

Author

Antti Karttunen, Feb 12 2019

Keywords

Comments

Restricted growth sequence transform of A322994.

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; };
    A000265(n) = (n/2^valuation(n, 2));
    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)};
    A156552(n) = if(1==n, 0, if(!(n%2), 1+(2*A156552(n/2)), 2*A156552(A064989(n))));
    A322993(n) = if(1==n,0,A000265(A156552(n)));
    A322994(n) = sumdiv(n,d,moebius(n/d)*A322993(d));
    v323914 = rgs_transform(vector(up_to,n,A322994(n)));
    A323914(n) = v323914[n];

A324910 Multiplicative with a(p^e) = (2^e)-1.

Original entry on oeis.org

1, 1, 1, 3, 1, 1, 1, 7, 3, 1, 1, 3, 1, 1, 1, 15, 1, 3, 1, 3, 1, 1, 1, 7, 3, 1, 7, 3, 1, 1, 1, 31, 1, 1, 1, 9, 1, 1, 1, 7, 1, 1, 1, 3, 3, 1, 1, 15, 3, 3, 1, 3, 1, 7, 1, 7, 1, 1, 1, 3, 1, 1, 3, 63, 1, 1, 1, 3, 1, 1, 1, 21, 1, 1, 3, 3, 1, 1, 1, 15, 15, 1, 1, 3, 1, 1, 1, 7, 1, 3, 1, 3, 1, 1, 1, 31, 1, 3, 3, 9, 1, 1, 1, 7, 1
Offset: 1

Views

Author

Antti Karttunen, Apr 14 2019

Keywords

Crossrefs

Programs

  • Mathematica
    Array[Times @@ (2^(FactorInteger[#][[All, -1]]) - 1) &, 105] (* Michael De Vlieger, Apr 14 2019 *)
  • PARI
    A324910(n) = factorback(apply(e -> -1+(2^e), factor(n)[,2]~));

Formula

Multiplicative with a(p^e) = A000225(e).
Multiplicative with a(p^e) = A322993(p^e).
a(n) = A246674(A156552(n)).

A342657 The difference between floor(log_2(.)) of and the number of prime factors in A156552(n) (when counted with multiplicity).

Original entry on oeis.org

0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 2, 0, 3, 1, 1, 0, 2, 0, 3, 1, 3, 0, 3, 0, 4, 1, 3, 0, 2, 0, 3, 3, 5, 1, 1, 0, 7, 3, 3, 0, 4, 0, 5, 2, 5, 0, 4, 0, 2, 4, 6, 0, 3, 1, 5, 5, 7, 0, 4, 0, 9, 3, 2, 3, 4, 0, 6, 7, 4, 0, 3, 0, 10, 2, 7, 1, 5, 0, 5, 1, 11, 0, 3, 3, 11, 5, 3, 0, 2, 1, 8, 7, 11, 4, 4, 0, 3, 3, 3, 0, 5, 0, 7, 2
Offset: 2

Views

Author

Antti Karttunen, Mar 18 2021

Keywords

Crossrefs

Programs

  • PARI
    A156552(n) = {my(f = factor(n), p, p2 = 1, res = 0); for(i = 1, #f~, p = 1 << (primepi(f[i, 1]) - 1); res += (p * p2 * (2^(f[i, 2]) - 1)); p2 <<= f[i, 2]); res};
    A342657(n) = { my(u=A156552(n)); (#binary(u)-bigomega(u))-1; };

Formula

a(n) = (A252464(n)-A342655(n))-1 = (A325134(n)-A342655(n)) - 2.
a(p) = a(p^2) = 0 for all primes p. (Second part added Jul 27 2023)
a(A003961(n)) = a(2*A246277(n)) = a(n).

A342666 a(n) = A336466(A156552(n)).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 5, 1, 1, 1, 1, 1, 3, 1, 9, 1, 5, 1, 11, 1, 3, 3, 3, 1, 3, 1, 15, 1, 21, 1, 1, 1, 1, 5, 3, 1, 9, 1, 33, 5, 9, 1, 23, 1, 1, 3, 65, 1, 7, 1, 35, 21, 5, 1, 21, 1, 341, 9, 3, 1, 11, 1, 27, 1, 5, 1, 5, 1, 15, 3, 51, 1, 27, 1, 39, 1, 1365, 1, 1, 5, 49, 9, 1, 1, 1, 1, 117, 5, 825, 3, 9, 1, 9, 3, 1, 1, 7, 1
Offset: 2

Views

Author

Antti Karttunen, Mar 18 2021

Keywords

Crossrefs

Programs

  • PARI
    A000265(n) = (n>>valuation(n,2));
    A336466(n) = { my(f=factor(n)); prod(k=1,#f~,if(2==f[k,1],1,(A000265(f[k,1]-1))^f[k,2])); };
    A156552(n) = {my(f = factor(n), p, p2 = 1, res = 0); for(i = 1, #f~, p = 1 << (primepi(f[i, 1]) - 1); res += (p * p2 * (2^(f[i, 2]) - 1)); p2 <<= f[i, 2]); res};
    A342666(n) = A336466(A156552(n));
    
  • PARI
    \\ Version using the factorization file available at https://oeis.org/A156552/a156552.txt
    v156552sigs = readvec("a156552.txt");
    A000265(n) = (n>>valuation(n,2));
    A342666(n) = if(isprime(n),1,my(prsig=v156552sigs[n],ps=prsig[1],es=prsig[2]); prod(i=1,#ps,A000265(ps[i]-1)^es[i])); \\ Antti Karttunen, Jan 29 2022

Formula

a(n) = A336466(A156552(n)) = A336466(A322993(n)).
a(p) = 1 for all primes p.
a(A003961(n)) = a(n).

A350068 Lexicographically earliest infinite sequence such that a(i) = a(j) => A046523(i) = A046523(j) and A350063(i) = A350063(j), for all i, j >= 1.

Original entry on oeis.org

1, 2, 2, 3, 2, 4, 2, 5, 3, 6, 2, 7, 2, 4, 4, 8, 2, 7, 2, 7, 6, 9, 2, 10, 3, 9, 5, 11, 2, 12, 2, 13, 4, 9, 4, 14, 2, 4, 9, 15, 2, 16, 2, 7, 7, 17, 2, 18, 3, 19, 9, 7, 2, 10, 6, 10, 9, 20, 2, 21, 2, 9, 7, 22, 4, 12, 2, 11, 4, 16, 2, 23, 2, 9, 7, 11, 4, 12, 2, 18, 8, 9, 2, 24, 9, 25, 17, 26, 2, 24, 6, 11, 20, 27, 9
Offset: 1

Views

Author

Antti Karttunen, Jan 29 2022

Keywords

Comments

Restricted growth sequence transform of the ordered pair [A046523(n), A350063(n)].
For all i, j >= 1: A305897(i) = A305897(j) => a(i) = a(j).

Crossrefs

Cf. A000040 (positions of 2's), A001248 (of 3's).

Programs

  • PARI
    up_to = 3003;
    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; };
    A000265(n) = (n>>valuation(n,2));
    A046523(n) = { my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]); };  \\ From A046523
    A156552(n) = { my(f = factor(n), p, p2 = 1, res = 0); for(i = 1, #f~, p = 1 << (primepi(f[i, 1]) - 1); res += (p * p2 * (2^(f[i, 2]) - 1)); p2 <<= f[i, 2]); res };
    A350063(n) = if(1==n,0,A046523(A000265(A156552(n))));
    Aux350068(n) = [A046523(n),A350063(n)];
    v350068 = rgs_transform(vector(up_to, n, Aux350068(n)));
    A350068(n) = v350068[n];

A331602 a(1) = 0; for n > 1, a(n) = A007947(A156552(n)).

Original entry on oeis.org

0, 1, 2, 3, 2, 5, 2, 7, 6, 3, 2, 11, 2, 17, 10, 15, 2, 13, 2, 19, 6, 33, 2, 23, 6, 65, 14, 35, 2, 21, 2, 31, 34, 129, 10, 3, 2, 257, 66, 39, 2, 37, 2, 67, 22, 57, 2, 47, 6, 5, 130, 131, 2, 29, 6, 71, 258, 205, 2, 43, 2, 2049, 38, 21, 34, 69, 2, 259, 514, 41, 2, 55, 2, 4097, 26, 515, 10, 133, 2, 79, 30, 8193, 2, 15, 66, 16385, 114, 15, 2, 15, 6, 1027, 410, 10923
Offset: 1

Views

Author

Antti Karttunen, Jan 22 2020

Keywords

Crossrefs

Cf. also A322993.

Programs

  • Mathematica
    Array[Times @@ FactorInteger[#][[All, 1]] &@ Floor@ Total@ Flatten@ MapIndexed[#1 2^(#2 - 1) &, Flatten[Table[2^(PrimePi@ #1 - 1), {#2}] & @@@ FactorInteger@ #]] &, 94] (* Michael De Vlieger, Jan 24 2020 *)
  • PARI
    A007947(n) = factorback(factorint(n)[, 1]);
    A156552(n) = {my(f = factor(n), p2 = 1, res = 0); for(i = 1, #f~, p = 1 << (primepi(f[i, 1]) - 1); res += (p * p2 * (2^(f[i, 2]) - 1)); p2 <<= f[i, 2]); res}; \\ From A156552
    A331602(n) = A007947(A156552(n));

Formula

a(1) = 0; and for n > 1, a(n) = A007947(A156552(n)).
A000035(a(n)) = 1 - A000035(n). [Flips the parity]
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