A225505 - OEIS

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A225505

a(n) = triangular(a(n-1)+a(n-2)) if n > 1, else a(n) = n.

0

0, 1, 1, 3, 10, 91, 5151, 13741903, 94490753712985, 4464252567106907867941273716, 9964775491460730298984873904585383048580645394630925051

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,4

LINKS

Table of n, a(n) for n=0..10.

PROG

(Python)

prpr, prev = 0, 1

for i in range(1, 17):

print(prpr, end=', ')

n = prpr+prev

cur = n*(n+1)//2

prpr, prev = prev, cur

CROSSREFS

Cf. A000217, A072638.

Sequence in context: A224774 A034792 A135457 * A073733 A005205 A216450

Adjacent sequences: A225502 A225503 A225504 * A225506 A225507 A225508

KEYWORD

nonn,changed

AUTHOR

Alex Ratushnyak, May 09 2013

STATUS

approved

NODES