A181103 - OEIS

A181103

a(n) is the least prime greater than a(n-1) such that abs(a(n-2) + a(n-1) - a(n)) is prime; a(1)=2, a(2)=3.

2, 3, 7, 13, 17, 19, 23, 29, 41, 47, 59, 83, 89, 101, 107, 137, 173, 179, 239, 251, 257, 269, 293, 311, 347, 389, 419, 449, 467, 557, 563, 599, 641, 647, 701, 761, 809, 827, 839, 857, 887, 947, 953, 971, 977, 1019, 1049, 1091, 1109, 1151, 1163, 1217, 1229

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OFFSET

1,1

COMMENTS

Partial products are in A181737.

LINKS

Nathaniel Johnston, Table of n, a(n) for n = 1..10000

MAPLE

A181103 := proc(n) option remember: local p: if(n<=2)then return n+1: fi: p:=procname(n-1): do p:=nextprime(p): if(isprime(abs(p-procname(n-2)-procname(n-1))))then return p: fi: od: end: seq(A181103(n), n=1..53); # Nathaniel Johnston, May 27 2011

MATHEMATICA

nxt[{a_, b_}]:=Module[{lp=NextPrime[b]}, While[!PrimeQ[Abs[a+b-lp]], lp= NextPrime[ lp]]; {b, lp}]; Transpose[NestList[nxt, {2, 3}, 60]][[1]] (* Harvey P. Dale, Feb 08 2015 *)

PROG

(Magma) A181103:=function(n); S:=[2, 3]; if n le 2 then return S[n]; end if; p:=5; for k in [3..n] do while not IsPrime(Abs(S[k-2]+S[k-1]-p)) do p:=NextPrime(p); end while; Append(~S, p); if k eq n then return p; end if; p:=NextPrime(p); end for; end function; [ A181103(n): n in [1..55] ]; // Klaus Brockhaus, Dec 19 2010

CROSSREFS

Cf. A181737.

Sequence in context: A336378 A141633 A045327 * A329487 A220814 A045328

Adjacent sequences: A181100 A181101 A181102 * A181104 A181105 A181106

KEYWORD

nonn,easy

AUTHOR

Giovanni Teofilatto, Oct 03 2010

EXTENSIONS

Definition refined and sequence extended by R. J. Mathar, Oct 12 2010

Index in definition corrected by R. J. Mathar, Oct 26 2010

STATUS

approved