A328402 - OEIS

%I #11 Oct 18 2019 11:28:59

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

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

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

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

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

%t 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 *)

%o (PARI)

%o A002110(n) = prod(i=1,n,prime(i));

%o isA048103(n) = { my(f = factor(n)); for(k=1, #f~, if(f[k, 2]>=f[k, 1], return(0))); (1); };

%o A328402(n) = sum(k=A002110(n-1),A002110(n)-1,isA048103(k));

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

%K nonn,more

%O 1,2

%A _Antti Karttunen_, Oct 17 2019