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A171152 Partial sums of A118011. 1
3, 9, 17, 28, 41, 56, 74, 94, 116, 140, 167, 196, 227, 260, 295, 333, 373, 415, 459, 505, 553, 604, 657, 712, 769, 828, 889, 952, 1018, 1086, 1156, 1228, 1302, 1378, 1456, 1536, 1619, 1704, 1791, 1880, 1971, 2064, 2159, 2256, 2355, 2457, 2561, 2667, 2775, 2885, 2997, 3111 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..52.

FORMULA

Set R = round(sqrt(2*n)), then a(n) = n^2+n+R*((6*n+1)-R^2)/6.

EXAMPLE

a(1) = 3;

a(2) = 3+6 = 9;

a(3) = 3+6+8 = 17;

a(4) = 3+6+8+11 = 28.

PROG

(PARI) vector(80, n, R = round(sqrt(2*n)); n^2+n+R*((6*n+1)-R^2)/6) \\ Michel Marcus, Apr 17 2015

CROSSREFS

Cf. A118011 (complement of the Connell sequence).

Sequence in context: A202253 A057258 A018466 * A035107 A090262 A190815

Adjacent sequences:  A171149 A171150 A171151 * A171153 A171154 A171155

KEYWORD

nonn

AUTHOR

Gerald Hillier, Dec 04 2009

EXTENSIONS

More terms from Michel Marcus, Apr 17 2015

STATUS

approved

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Last modified December 4 04:22 EST 2020. Contains 338921 sequences. (Running on oeis4.)