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A180027 Partial sums of sigma_A100706(n). 1
1, 112, 11223, 1122334, 112233445, 11223344556, 1122334455667, 112233445566778, 11223344556677889, 1122334455667789000, 112233445566778900111, 11223344556677890011222 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Up to n=9 the digits of a(n) sum up to n^2. Similar to this, A014824 (1,12,123,1234,...) is a representation of the triangular numbers; (1,1112,1112223,1112223334,...)of the pentagonal numbers;(1,11112,111122223,..) of the hexagonal numbers, and so on. A nice thing about this sequence(s) is that the (represented) value of the integer matches the partial sums of the number of digits in the sequence. a(n)=100*a(n-1)+ A100706(n) gives a mirrored version of this sequence, and a(n)=10*a(n-1)+ A100706(n) the symmetrical version (A002477).

LINKS

Table of n, a(n) for n=1..12.

CROSSREFS

Cf. A014824, A100706, A002477.

Sequence in context: A075910 A089277 A203788 * A240229 A187672 A049217

Adjacent sequences:  A180024 A180025 A180026 * A180028 A180029 A180030

KEYWORD

nonn

AUTHOR

Mark Dols, Aug 07 2010

STATUS

approved

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Last modified May 31 00:53 EDT 2020. Contains 334747 sequences. (Running on oeis4.)