A082088 -id:A082088 - cp's OEIS frontend

A082880 Largest value of A075860(j) when j runs through composite numbers between n-th and (n+1)-th primes. That is, the largest fixed-point[=prime] reached by iteration of A008472(=sum of prime factors) initiated with composite values between two consecutive primes.

0, 2, 5, 7, 5, 3, 5, 13, 5, 7, 19, 7, 5, 13, 7, 31, 7, 7, 19, 5, 7, 43, 13, 19, 7, 13, 2, 5, 7, 61, 7, 19, 3, 73, 7, 7, 7, 43, 13, 19, 7, 13, 5, 7, 2, 103, 109, 3, 5, 31, 61, 7, 13, 19, 13, 31, 7, 139, 19, 2, 73, 151, 7, 5, 3, 43, 13, 31, 19, 13, 181, 19, 13, 7, 193, 23, 199, 29, 103, 73

Offset: 1

Labos Elemer, Apr 16 2003

nonn

Cf. A075860, A008472, A082087, A082088, A082881, A029908.

ffi[x_] := Flatten[FactorInteger[x]]; lf[x_] := Length[FactorInteger[x]]; ba[x_] := Table[Part[ffi[x], 2*w-1], {w, 1, lf[x]}]; sopf[x_] := Apply[Plus, ba[x]]; Table[Max[0, Table[FixedPoint[sopf, w], {w, 1+Prime[n], Prime[n+1]-1}]], {n, 80}]

a(n) = Max_{x=1+prime(n)..prime(n+1)-1} A075860(x).

A082881 Least value of A075860(j) when j runs through composite numbers between n-th and (n+1)-th primes. That is, the smallest fixed-point[=prime] reached by iteration of function A008472(=sum of prime factors) initiated with composite values between two consecutive primes.

Original entry on oeis.org

0, 2, 5, 2, 5, 2, 5, 7, 2, 7, 2, 2, 5, 2, 2, 2, 7, 2, 2, 5, 2, 3, 2, 5, 3, 13, 2, 5, 3, 2, 2, 2, 3, 2, 7, 5, 3, 13, 2, 3, 7, 2, 5, 3, 2, 2, 2, 2, 5, 7, 2, 7, 2, 2, 2, 2, 7, 2, 3, 2, 2, 2, 2, 5, 2, 2, 5, 2, 19, 2, 2, 2, 5, 2, 2, 3, 2, 3, 2, 2, 17, 2, 5, 5, 2, 2, 2, 7, 23, 2, 2, 3, 3, 3, 5, 2, 2, 19, 2, 5, 2, 3, 2

Offset: 1

Labos Elemer, Apr 16 2003

nonn

			Between p(23)=83 and p(24)=89, the relevant fixed points are {5,13,2,2,13}, of which the smallest is 2=a(24).

Cf. A075860, A008472, A082087, A082088, A082880, A029908.

ffi[x_] := Flatten[FactorInteger[x]]; lf[x_] := Length[FactorInteger[x]]; ba[x_] := Table[Part[ffi[x], 2*w-1], {w, 1, lf[x]}]; sopf[x_] := Apply[Plus, ba[x]]; Table[Min[Table[FixedPoint[sopf, w], {w, 1+Prime[n], Prime[n+1]-1}]], {n, 2, 103}]

a(n) = Min_{x=1+prime(n)..prime(n+1)-1} A075860(x).

A082882 Number of distinct values of A075860(j) when j runs through composite numbers between n-th and (n+1)-th primes. That is, the counts of different fixed-points[=prime] reached by iteration of function A008472(=sum of prime factors) initiated with composite values between two consecutive primes.

Original entry on oeis.org

0, 1, 1, 3, 1, 2, 1, 2, 3, 1, 4, 2, 1, 3, 3, 5, 1, 4, 3, 1, 3, 3, 3, 3, 2, 1, 1, 1, 3, 8, 3, 2, 1, 6, 1, 2, 3, 3, 3, 5, 1, 5, 1, 2, 1, 7, 4, 2, 1, 2, 4, 1, 5, 3, 4, 4, 1, 5, 3, 1, 6, 6, 2, 1, 2, 7, 3, 4, 1, 3, 4, 6, 3, 3, 3, 4, 6, 3, 5, 5, 1, 6, 1, 3, 3, 4, 5, 1, 1, 2, 6, 4, 3, 4, 3, 2, 6, 1, 8, 3, 6, 4, 5, 1, 4

Offset: 1

Labos Elemer, Apr 16 2003

nonn

This count is smaller than A001223[n]-1 and albeit not frequently but it can be one even if primes of borders are not twin primes. Such primes are collected into A082883.

			Between p(23)=83 and p(24)=89, the relevant fixed points are
{5,13,2,2,13}, i.e., four are distinct from the 5 values, a(24)=4;
between p(2033)=17707 and p(2034)=170713, the fixed-point set is {5,5,5,5,5}, so a(2033)=1, so a(88)=1.

Cf. A075860, A008472, A082087, A082088, A082880, A082081, A001223.

ffi[x_] := Flatten[FactorInteger[x]] lf[x_] := Length[FactorInteger[x]] ba[x_] := Table[Part[ffi[x], 2*w-1], {w, 1, lf[x]}] sopf[x_] := Apply[Plus, ba[x]] Table[Length[Union[Table[FixedPoint[sopf, w], {w, 1+Prime[n], Prime[n+1]-1}]]], {n, 1, 1000}]

a(n) = Card(Union(A075860(x)); x=1+p(n), ..., -1+p(n+1)).

A082089 a(n)-th prime is the fixed point if function A008472[=sum of prime factors with no repetition] is iterated when started at factorial of n-th prime.

Original entry on oeis.org

1, 3, 4, 7, 2, 13, 11, 3, 4, 3, 4, 45, 1, 60, 14, 4, 3, 3, 21, 1, 4, 4, 6, 3, 4, 3, 2, 4, 6, 2, 4, 4, 4, 4, 105, 4, 4, 3, 4, 4, 3, 4, 3, 4, 1, 4, 8, 2, 2, 19, 3, 1, 20, 14, 4, 20, 52, 4, 4, 977, 1, 3, 65, 1108, 1, 2, 46, 3, 3, 1, 3, 1, 2, 4, 829, 2, 25, 3, 8, 25, 4, 378, 3, 3, 29, 3, 6, 8, 1, 1, 28

Offset: 2

Labos Elemer, Apr 09 2003

nonn

a(n) < n holds usually, except few large values arising unexpectedly.

			n=100, p(100)=541, starts at factorial of 100th prime and ends in 24133, the 2687th prime, so a(100)=2687;
n=99, initial value=523!, fixed point is 19, the 8th prime, a(99)=8.

Cf. A008472, A034387, A007504, A075860, A082087, A082088.

ffi[x_] := Flatten[FactorInteger[x]] lf[x_] := Length[FactorInteger[x]] ba[x_] := Table[Part[ffi[x], 2*w-1], {w, 1, lf[x]}] sopf[x_] := Apply[Plus, ba[x]] Table[PrimePi[FixedPoint[sopf, Prime[w]! ]], {w, 2, 100}]

a(n) = A000720(A082087(A000142(A000040(n)))) = pi(A082087(p(n)!)).

cp's OEIS Frontend

A082880 Largest value of A075860(j) when j runs through composite numbers between n-th and (n+1)-th primes. That is, the largest fixed-point[=prime] reached by iteration of A008472(=sum of prime factors) initiated with composite values between two consecutive primes.

Views

Author

Keywords

Crossrefs

Programs

Mathematica

Formula

A082881 Least value of A075860(j) when j runs through composite numbers between n-th and (n+1)-th primes. That is, the smallest fixed-point[=prime] reached by iteration of function A008472(=sum of prime factors) initiated with composite values between two consecutive primes.

Views

Author

Keywords

Examples

Crossrefs

Programs

Mathematica

Formula

Views

Author

Keywords

Comments

Examples

Crossrefs

Programs

Mathematica

Formula

A082089 a(n)-th prime is the fixed point if function A008472[=sum of prime factors with no repetition] is iterated when started at factorial of n-th prime.

Views

Author

Keywords

Comments

Examples

Crossrefs

Programs

Mathematica

Formula