A087359 For n > 2, a(n) is the smallest triangular number > a(n-1) and congruent to a(n-1) (mod a(n-2)).

1, 3, 6, 15, 21, 36, 78, 1770, 2628, 330078, 1160526, 1106921826, 27467109390, 3405462502501956, 464491597897585896, 35168538277628662422146736, 113107978211040574688911417114776, 158163225773885113469535108323447683287341095656

Offset

1,2

Links

Table of n, a(n) for n=1..18.

Example

a(7) == a(6) (mod a(5)), -> 78 -36 = 42 = 2*21.

Crossrefs

Cf. A087360.

Sequence in context: A117748 A061066 A093799 * A253651 A180322 A244164

Adjacent sequences: A087356 A087357 A087358 * A087360 A087361 A087362

Keyword

nonn

Author

Amarnath Murthy, Sep 08 2003

Extensions

More terms from David Wasserman, May 19 2005

Status

approved