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A199809 a(n) is the smallest number which is the sum of two positive n-gonal numbers in more than one way. 1
16, 50, 211, 384, 470, 1053, 1500, 2242, 3197, 3277, 5501, 6780, 8710, 9896, 10584, 15198, 15395, 21237, 23346, 28696, 33596, 37725, 40795, 48474, 55369, 54146, 69113, 75732, 84962, 92541, 95623, 98672, 123575, 127317, 146639, 141066, 154975, 173416, 201032 (list; graph; refs; listen; history; text; internal format)
OFFSET

3,1

COMMENTS

The sequence is not monotonically increasing as a(27) = 55369 > 54146 = a(28).

LINKS

Table of n, a(n) for n=3..41.

EXAMPLE

a(3)=16 since 16=1+15=6+10, such that 1,15,6,10 are all triangular numbers (A000217) and there are no other positive numbers less than 16 with such a property.

CROSSREFS

Sequence in context: A235566 A186842 A231840 * A121863 A121864 A221485

Adjacent sequences:  A199806 A199807 A199808 * A199810 A199811 A199812

KEYWORD

nonn

AUTHOR

Vladimir Shevelev, Dec 16 2013

EXTENSIONS

More terms from Peter J. C. Moses, Dec 16 2013

STATUS

approved

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Last modified February 21 16:41 EST 2018. Contains 299414 sequences. (Running on oeis4.)