A328402 Number of terms of A048103 found in range A002110(n-1) .. A002110(n)-1.

1, 3, 17, 130, 1517, 20013, 346902, 6634497, 154067794

Offset

1,2

Comments

Number of integers from A002110(n-1) to A002110(n)-1 that are in range of A276086.

a(n) is the total number of times n occurs in A328404.

Links

Table of n, a(n) for n=1..9.

Formula

a(n) <= A061720(n-1) for all n >= 1.

Mathematica

With[{s = FoldList[Times, 1, Prime@ Range@ 7]}, Array[Boole[# == 2] + Count[Range[s[[# - 1]], s[[#]] - 1], _?(Times @@ Boole@ Map[First@ # > Last@ # &, FactorInteger@ #] > 0 &)] &, Length@ s - 1, 2]] (* Michael De Vlieger, Oct 17 2019 *)

Prog

(PARI)
A002110(n) = prod(i=1, n, prime(i));
isA048103(n) = { my(f = factor(n)); for(k=1, #f~, if(f[k, 2]>=f[k, 1], return(0))); (1); };
A328402(n) = sum(k=A002110(n-1), A002110(n)-1, isA048103(k));

Crossrefs

Cf. A002110, A048103, A061720, A129251, A276086, A328404.

Sequence in context: A245059 A321587 A089815 * A247788 A355598 A006759

Adjacent sequences: A328399 A328400 A328401 * A328403 A328404 A328405

Keyword

nonn,more

Author

Antti Karttunen, Oct 17 2019

Status

approved