A341609 Characteristic function of A337372: a(n) = 1 if A337345(n) = 1, otherwise 0.

0, 0, 0, 1, 0, 1, 0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0

Offset

1

Comments

Characteristic function of the primitive terms of A246282.

Links

Antti Karttunen, Table of n, a(n) for n = 1..65537

Index entries for characteristic functions

Index entries for sequences computed from indices in prime factorization

Formula

a(n) = [A337345(n) = 1], where [ ] is the Iverson bracket.

Mathematica

f[1] = 1; f[n_] := Times @@ (NextPrime[#1]^#2 & @@@ FactorInteger[n]); a[n_] := Boole[DivisorSum[n, 1 &, f[#] > 2*# &] == 1]; Array[a, 100] (* Amiram Eldar, Feb 22 2021 *)

Prog

(PARI)
A003961(n) = { my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); };
A341609(n) = if(A003961(n) < 2*n, 0, fordiv(n, d, if((d<n)&&(A003961(d) > 2*d), return(0))); (1)); \\ After code in A341619

Crossrefs

Cf. A003961, A246282, A337345, A337372.

Cf. also A341619.

Sequence in context: A353555 A353476 A288377 * A064911 A174898 A099618

Adjacent sequences: A341606 A341607 A341608 * A341610 A341611 A341612

Keyword

nonn

Author

Antti Karttunen, Feb 22 2021

Status

approved