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A100591
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.
0
1, 4, 7, 10, 35, 25, 49, 61, 121, 140, 211, 268, 224, 392, 472, 517, 565, 529, 707, 1006, 1039, 994, 1213, 989, 1274, 1717, 1769, 1822, 2047, 2272, 2419, 2573, 2642, 3029, 3149, 3152, 3848, 3359, 4199, 4019, 4307, 4847, 5027, 4877, 5492, 6077
OFFSET
0,2
COMMENTS
Computed by Ray Chandler.
FORMULA
a(n) = min(i such that i = A001358(j) + A000217(k) in n ways).
EXAMPLE
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.
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Jonathan Vos Post, Nov 30 2004
STATUS
approved