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A292564 Take 1, skip 3 * 1 - 1, take 2, skip 3 * 2 - 1, take 3, skip 3 * 3 - 1, ... 2
0, 3, 4, 10, 11, 12, 21, 22, 23, 24, 36, 37, 38, 39, 40, 55, 56, 57, 58, 59, 60, 78, 79, 80, 81, 82, 83, 84, 105, 106, 107, 108, 109, 110, 111, 112, 136, 137, 138, 139, 140, 141, 142, 143, 144, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 210, 211, 212 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Seiichi Manyama, Table of n, a(n) for n = 0..10000

Michael Boardman, Proof Without Words: Pythagorean Runs, Math. Mag., 73 (2000), 59.

FORMULA

a(n) = n + floor((sqrt(8*n+1)-1)/2)*(3*floor((sqrt(8*n+1)-1)/2)+1)/2. - Robert Israel, Sep 20 2017

MAPLE

seq(seq(2*k^2+k+j, j=0..k), k=0..10); # Robert Israel, Sep 20 2017

CROSSREFS

Cf. A059255, A063656, A292565.

Sequence in context: A288660 A212440 A066861 * A191192 A139063 A224853

Adjacent sequences:  A292561 A292562 A292563 * A292565 A292566 A292567

KEYWORD

nonn,easy

AUTHOR

Seiichi Manyama, Sep 19 2017

STATUS

approved

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Last modified May 28 15:33 EDT 2020. Contains 334684 sequences. (Running on oeis4.)