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a(n) = 1 if prime(n) + 2 = prime(n+1), otherwise 0.
3

%I #8 Nov 01 2019 16:43:31

%S 0,1,1,0,1,0,1,0,0,1,0,0,1,0,0,0,1,0,0,1,0,0,0,0,0,1,0,1,0,0,0,0,1,0,

%T 1,0,0,0,0,0,1,0,1,0,1,0,0,0,1,0,0,1,0,0,0,0,1,0,0,1,0,0,0,1,0,0,0,0,

%U 1,0,0,0,0,0,0,0,0,0,0,0,1,0,1,0,0,0,0,0,1,0,0,0,0,0,0,0,0,1,0,0,0,0,0,1,0

%N a(n) = 1 if prime(n) + 2 = prime(n+1), otherwise 0.

%C Same as A062301 except for starting point.

%C a(n)=1 iff prime(n) is the smaller of a pair of twin primes, else a(n)=0. This sequence can be derived from the sequence b(n)=1 iff n and n+2 are both prime, else b(n)=0. This latter sequence has as its inverse Moebius transform the sequence c(n) = the number of distinct factors of n which are the smaller of a pair of twin primes. For example, c(15)=2 because 15 is divisible by 3 and 5, each of which is the smaller of a pair of twin primes. - _Jonathan Vos Post_, Jan 07 2005

%F a(n) = A062301(n+1) = 1 - A100810(n).

%t Table[If[Prime[n] + 2 == Prime[n + 1], 1, 0], {n, 120}] (* _Ray Chandler_, Jan 09 2005 *)

%K easy,nonn

%O 1,1

%A _Giovanni Teofilatto_, Jan 06 2005

%E Corrected and extended by _Ray Chandler_, Jan 09 2005