A061885 - OEIS

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A061885

n + largest triangular number less than or equal to n.

0, 2, 3, 6, 7, 8, 12, 13, 14, 15, 20, 21, 22, 23, 24, 30, 31, 32, 33, 34, 35, 42, 43, 44, 45, 46, 47, 48, 56, 57, 58, 59, 60, 61, 62, 63, 72, 73, 74, 75, 76, 77, 78, 79, 80, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 132 (list; graph; refs; listen; history; internal format)

	OFFSET	`0,2`
	COMMENTS	`a(9)=9+6=15; a(10)=10+10=20; a(11)=11+10=21.`
	LINKS	`Reinhard Zumkeller, Table of n, a(n) for n = 0..10000`
	FORMULA	`a(n) = n+A057944(n) = 2n-A002262(n) = n+[(sqrt(1+8n)-1)/2][(sqrt(1+8*n)+1)/2]/2.` `a(n) = A004201(n+1) - 1. [From Franklin T. Adams-Watters (FrankTAW(AT)Netscape.net), Jul 05 2009]`
	PROG	`(Haskell)` `a061885 n = n + a057944 n -- Reinhard Zumkeller, Feb 03 2012`
	CROSSREFS	`Cf. A060985.` `Sequence in context: A069579 A065193 A116047 * A138683 A072426 A189137` `Adjacent sequences: A061882 A061883 A061884 * A061886 A061887 A061888`
	KEYWORD	`nonn,changed`
	AUTHOR	`Henry Bottomley (se16(AT)btinternet.com), May 12 2001`

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Last modified February 14 06:58 EST 2012. Contains 205577 sequences.