A133661 - OEIS

%I #7 May 18 2019 10:58:11

%S 1,8,25,86,209,472,25719,238350,41931245,14426603100

%N No sum of 2 or more terms equals a prime, terms alternate parity and there are no primes in the list.

%C a(10) > 263811880. - _Robert G. Wilson v_, Jan 01 2008

%e 25 is a term, because 25 is odd (previous term was even), 25 is composite and 25+1, 25+8 and 25+8+1 are all composite.

%t (* first do *) Needs["Combinatorica`"] (* then *) lst = {1, 8}; g[k_] := Block[{j = 1, l = 2^Length@lst}, While[j < l && !PrimeQ[Plus @@ NthSubset[j, lst] + k], j++ ]; If[j == l, False, True]]; f[n_] := Block[{k = lst[[ -1]] + 1}, While[PrimeQ@k || g[k] == True, k++; k++ ]; AppendTo[lst, k]; k]; Do[ Print@ f@ n, {n, 10}] (* _Robert G. Wilson v_, Jan 01 2008 *)

%Y Cf. A052349, A133660.

%K more,nonn

%O 1,2

%A _Randy L. Ekl_, Dec 28 2007

%E a(9) from _Robert G. Wilson v_, Jan 01 2008

%E a(10) from _Donovan Johnson_, Feb 15 2008