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.

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.

Links

Table of n, a(n) for n=0..45.

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

Cf. A000217, A001358, A076768, A100570.

Sequence in context: A123986 A294914 A088405 * A135262 A061515 A071084

Adjacent sequences: A100588 A100589 A100590 * A100592 A100593 A100594

Keyword

easy,nonn

Author

Jonathan Vos Post, Nov 30 2004

Status

approved