id:A018855 - OEIS Search Results

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Smallest triangular number that begins with n.

+0
2

1, 21, 3, 45, 55, 6, 78, 820, 91, 10, 1128, 120, 136, 1431, 15, 1653, 171, 1830, 190, 2016, 21, 2211, 231, 2415, 253, 2628, 276, 28, 2926, 300, 3160, 325, 3321, 3403, 351, 36, 378, 3828, 3916, 406, 4186, 4278, 435, 4465, 45, 465, 4753, 4851, 496, 5050, 5151, 528 (list; graph; listen)

	OFFSET	`1,2`
	MATHEMATICA	`Do[k = Ceiling[ Sqrt[n]]; While[ FromDigits[ Take[ IntegerDigits[ k(k + 1)/2], Floor[ Log[10, n] + 1]]] != n, k++ ]; Print[ k(k + 1)/2], {n, 1, 50} ]`
	CROSSREFS	`Cf. A018801.` `Sequence in context: A080472 A118389 A077690 this_sequence A040428 A040429 A082128` `Adjacent sequences: A018852 A018853 A018854 this_sequence A018856 A018857 A018858`
	KEYWORD	`base,easy,nonn`
	AUTHOR	`David W. Wilson (davidwwilson(AT)comcast.net)`

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Last modified December 2 15:58 EST 2008. Contains 150992 sequences.

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