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A067525
Define I(n) = number obtained by incrementing each digit from 0 to 8 of n by 1. A '9' is replaced by a '0'. Sequence gives digitriangular numbers n*I(n)/2.
0
1, 3, 6, 10, 15, 21, 28, 36, 0, 105, 121, 138, 156, 175, 195, 216, 238, 261, 190, 310, 336, 363, 391, 420, 450, 481, 513, 546, 435, 615, 651, 688, 726, 765, 805, 846, 888, 931, 780, 1020, 1066, 1113, 1161, 1210, 1260, 1311, 1363, 1416, 1225, 1525, 1581
OFFSET
1,2
EXAMPLE
a(34) = 34*45/2 = 765. a(129) = 129*230/2 =14835
MATHEMATICA
Table[n/2 FromDigits[(IntegerDigits[n]+1)/.(10->0)], {n, 60}] (* Harvey P. Dale, Jul 08 2011 *)
CROSSREFS
Sequence in context: A109444 A124157 A033440 * A130487 A231684 A363777
KEYWORD
base,easy,nonn
AUTHOR
Amarnath Murthy, Feb 15 2002
EXTENSIONS
More terms from Sascha Kurz, Mar 28 2002
Corrected definition -- Harvey P. Dale, Jul 08 2011
STATUS
approved