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A296210 Characteristic function for A104210: a(n) = 1 if n is divisible by at least 2 consecutive primes, 0 otherwise. 4
0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1

LINKS

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

Index entries for characteristic functions

MATHEMATICA

Array[Boole@ MemberQ[Differences@ PrimePi@ FactorInteger[#][[All, 1]], 1] &, 105] (* Michael De Vlieger, Dec 16 2017 *)

PROG

(PARI) A296210(n) = { if(1==n, return(0)); my(ps=factor(n)[, 1], pis=vector(length(ps), i, primepi(ps[i])), diffsminusones = vector(length(pis)-1, i, (pis[i+1]-pis[i])-1)); !factorback(diffsminusones); };

CROSSREFS

Cf. A104210, A166469, A192280.

Sequence in context: A133944 A210455 A294936 * A094912 A103673 A028862

Adjacent sequences:  A296207 A296208 A296209 * A296211 A296212 A296213

KEYWORD

nonn

AUTHOR

Antti Karttunen, Dec 15 2017

STATUS

approved

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Last modified October 21 16:50 EDT 2019. Contains 328302 sequences. (Running on oeis4.)