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A136288 Primes which are the absolute value of the alternating sum and difference of the first n primes. 1

%I #34 Oct 28 2021 02:06:48

%S 2,3,5,7,13,19,29,53,61,71,79,83,97,103,113,139,149,151,157,163,167,

%T 191,199,233,251,281,337,347,353,397,421,433,461,563,599,643,719,773,

%U 797,811,859,883,953,977,1031,1039,1061,1063,1091,1097,1153,1187,1201,1213

%N Primes which are the absolute value of the alternating sum and difference of the first n primes.

%H Dmitry Kamenetsky, <a href="/A136288/b136288.txt">Table of n, a(n) for n = 1..10000</a> (first 144 terms by Paolo P. Lava and Giorgio Balzarotti)

%F A000040 INTERSECT A008347. - _R. J. Mathar_, Apr 04 2008

%e 5 = abs(2-3+5-7+11-13) (first 6 primes),

%e 7 = abs(2-3+5-7+11-13+17-19) (first 8 primes),

%e etc.

%p P:=proc(n) local i,s; s:=0; for i from 1 by 1 to n do s:=s+(-1)^i*ithprime(i); if isprime(abs(s)) then print(abs(s)); fi; od; end: P(1000);

%t Select[Abs@Accumulate@Table[(-1)^(k+1)*Prime@k,{k,355}],PrimeQ] (* _Giorgos Kalogeropoulos_, Sep 22 2021 *)

%Y Cf. A000040, A008347, A013918.

%K easy,nonn

%O 1,1

%A _Paolo P. Lava_ and _Giorgio Balzarotti_, Mar 20 2008

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