A100591 - OEIS

%I #3 Mar 30 2012 18:40:21

%S 1,4,7,10,35,25,49,61,121,140,211,268,224,392,472,517,565,529,707,

%T 1006,1039,994,1213,989,1274,1717,1769,1822,2047,2272,2419,2573,2642,

%U 3029,3149,3152,3848,3359,4199,4019,4307,4847,5027,4877,5492,6077

%N Least positive integer that can be represented as sum of semiprime and a triangular number in exactly n ways. Triangular numbers include t(0)=0 and (1)=1.

%C Computed by Ray Chandler.

%F a(n) = min(i such that i = A001358(j) + A000217(k) in n ways).

%e a(0) = 1 because 1 is the smallest positive integer that cannot be represented as sum of semiprime and a triangular number (since 4 is the smallest semiprime). a(1) = 4 because 4 is the smallest such sum, namely semiprime(1)=4 + t(0)=0. Similarly a(2) = 7 because 7 = 4 + 3 and 7 = 6 + 1, where 4 and 6 are semiprimes, 3 and 1 are triangular.

%Y Cf. A000217, A001358, A076768, A100570.

%K easy,nonn

%O 0,2

%A _Jonathan Vos Post_, Nov 30 2004