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A038457
|First digit-last digit| for triangular numbers.
1
0, 0, 0, 0, 1, 4, 1, 6, 3, 1, 0, 0, 1, 8, 4, 1, 5, 2, 0, 1, 2, 1, 1, 4, 3, 2, 2, 5, 2, 1, 1, 2, 3, 4, 0, 6, 0, 4, 6, 7, 8, 7, 6, 3, 9, 4, 0, 7, 5, 4, 4, 5, 7, 0, 4, 1, 5, 2, 0, 1, 1, 0, 2, 4, 2, 3, 1, 6, 4, 3, 3, 4, 6, 1, 3, 2, 4, 0, 2, 3, 3, 2, 0, 3, 3, 2, 2, 5, 3, 1, 1, 2, 4, 3, 1, 4, 2, 1, 3, 4, 5
OFFSET
0,6
FORMULA
a(n) = A040163(A000217(n)). - Michel Marcus, Sep 27 2013
MATHEMATICA
Abs[IntegerDigits[#][[1]]-IntegerDigits[#][[-1]]]&/@Accumulate[ Range[ 0, 120]] (* Harvey P. Dale, Mar 22 2020 *)
CROSSREFS
Cf. A000217.
Sequence in context: A098987 A174390 A153017 * A141649 A101347 A200344
KEYWORD
easy,nonn,base
AUTHOR
STATUS
approved