A053587 Indices of A052344 (ways to write n as sum of two nonzero triangular numbers) where record values are reached.

2, 16, 81, 471, 1056, 1381, 6906, 17956, 34531, 40056, 200281, 520731, 1001406, 1482081, 7410406, 19267056, 37052031, 60765331, 303826656, 789949306, 1519133281, 3220562556, 13429138206, 16102812781, 41867313231, 80514063906, 196454315931, 711744324931

Offset

1,1

Comments

The subsequence of primes begins: 2, 1381, 1519133281 [Jonathan Vos Post, Feb 01 2011].

Links

Table of n, a(n) for n=1..28.

Kenneth Korbin, Problem 665, The College Mathematics Journal Vol. 30 No. 5, Nov. 1999. Asks for the 48th number in this sequence.

Example

The order of the terms is ignored when deciding in how many ways the sum can be expressed. For example, a(2) does not equal 9, although 9 = 3 + 6 = 6 + 3.
a(2) = 16 because 16 = 1 + 15 = 6 + 10. a(3) = 81 because 81 = 3 + 78 = 15 + 66 = 36 + 55.

Crossrefs

Probably differs from A052348 only at n=1, 2, 4.

Cf. A000217, A052343, A052344, A052345, A052346, A052347, A052348.

Sequence in context: A012680 A012684 A234004 * A052346 A207482 A207880

Adjacent sequences: A053584 A053585 A053586 * A053588 A053589 A053590

Keyword

nonn,nice,easy

Author

Jeremy Rouse, Jan 19 2000

Extensions

More terms from Christian G. Bower, Jan 23 2000

a(25)-a(26) from Donovan Johnson, Jun 26 2010

a(27)-a(28) from Donovan Johnson, Mar 20 2013

Status

approved