A341629 Characteristic function of A055932: a(n) = 1 if n is a number all of whose prime divisors are consecutive primes starting at 2, otherwise 0.

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

Offset

1

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) >= A322585(n) for all n.

Mathematica

Array[Boole[MemberQ[{{0}, {1}}, Union@Prepend[Differences[#], First[#]] &@ PrimePi@ FactorInteger[#][[All, 1]] ] ] &, 120] (* Michael De Vlieger, Feb 25 2021 *)

Prog

(PARI) A341629(n) = if(1==n, 1, my(f=factor(n)[, 1]~); (primepi(f[#f])==#f));

Crossrefs

Cf. A055932 (positions of ones), A080259 (of zeros), A322585, A340346.

Sequence in context: A344438 A322585 A326956 * A365429 A322860 A378550

Adjacent sequences: A341626 A341627 A341628 * A341630 A341631 A341632

Keyword

nonn

Author

Antti Karttunen, Feb 25 2021

Status

approved