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a(n) = prime(n) - 3.
18

%I #23 Feb 04 2024 01:15:13

%S -1,0,2,4,8,10,14,16,20,26,28,34,38,40,44,50,56,58,64,68,70,76,80,86,

%T 94,98,100,104,106,110,124,128,134,136,146,148,154,160,164,170,176,

%U 178,188,190,194,196,208,220,224,226,230,236,238,248,254,260,266,268,274,278

%N a(n) = prime(n) - 3.

%C Numbers n such that n+3 is a prime.

%D M. Cerasoli, F. Eugeni and M. Protasi, Elementi di Matematica Discreta, Bologna 1988

%D Emanuele Munarini and Norma Zagaglia Salvi, Matematica Discreta, UTET, CittaStudiEdizioni, Milano 1997

%F a(n) = 2*A067076(n) = 2*(A006254(n+1)-2).

%e n=16 is here because 16+3=19 is a prime.

%t Prime[Range[22]]-3 (* _Vladimir Joseph Stephan Orlovsky_, Apr 29 2008 *)

%o (PARI) for(x=2,20,print1(prime(x)-3,",")) \\ _Jorge Coveiro_, Jan 30 2006

%Y Cf. A006254, A067076, A091738, A116127, A119981, A173064.

%K easy,sign

%O 1,3

%A _Giovanni Teofilatto_, Aug 05 2003

%E Extended by _Ray Chandler_, Nov 29 2003