A080817 - OEIS

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A080817

Leading diagonal of triangle in A080818.

3

1, 3, 6, 10, 6, 10, 15, 8, 13, 19, 26, 15, 22, 30, 16, 24, 33, 43, 25, 35, 46, 25, 36, 48, 61, 36, 49, 63, 35, 49, 64, 33, 48, 64, 81, 46, 63, 81, 43, 61, 80, 100, 58, 78, 99, 54, 75, 97, 49, 71, 94, 118, 66, 90, 115, 60, 85, 111, 138, 79, 106, 134, 72, 100, 129, 159, 93, 123

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..68.

FORMULA

From David Wasserman, May 13 2004: (Start)

a(n) = (ceiling(sqrt(n(n+1)/2)))^2 - n(n-1)/2.

a(n) = A048761(A000217(n)) - A000217(n-1). (End)

CROSSREFS

Cf. A080818, A080819, A080820.

Sequence in context: A065234 A333531 A082184 * A139762 A055262 A353199

Adjacent sequences: A080814 A080815 A080816 * A080818 A080819 A080820

KEYWORD

nonn

AUTHOR

Amarnath Murthy, Mar 21 2003

EXTENSIONS

More terms from David Wasserman, May 13 2004

STATUS

approved