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A138980 a(0)=1; for n>=1, a(n) = smallest prime > a(n-1) such that (sum{k=0 to n} a(k)) is composite. 3
1, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281 (list; graph; refs; listen; history; internal format)
OFFSET

0,2

COMMENTS

Although superficially similar to A049561, the two sequences are in fact quite different (see for example A0138982).

LINKS

R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 30 2008, Table of n, a(n) for n = 0..112

MAPLE

A138980 := proc(n) option remember ; local i, p ; if n = 0 then 1 ; else for p from nextprime(A138980(n-1)) do if isprime(p) then if not isprime( p+add(A138980(i), i=0..n-1) ) then RETURN(p) ; fi ; fi ; od: fi ; end: seq(A138980(n), n=0..120) ; # R. J. Mathar (mathar(AT)strw.leidenuniv.nl) Apr 30 2008

CROSSREFS

Cf. A138981, A138982, A049561.

Sequence in context: A073579 A065380 A038134 * A191378 A191376 A179429

Adjacent sequences:  A138977 A138978 A138979 * A138981 A138982 A138983

KEYWORD

nonn

AUTHOR

Leroy Quet Apr 05 2008

EXTENSIONS

More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 30 2008

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Last modified February 16 21:51 EST 2012. Contains 205978 sequences.