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A160944 a(n)= n * digital sum(n-1) * digital sum(n+1) 0
0, 6, 24, 60, 120, 210, 336, 504, 72, 180, 33, 96, 195, 336, 525, 768, 1071, 1440, 342, 600, 168, 330, 552, 840, 1200, 1638, 2160, 2772, 870, 1320, 465, 768, 1155, 1632, 2205, 2880, 3663, 4560, 1716, 2400, 984, 1470, 2064, 2772, 3600, 4554, 5640, 6864 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
FORMULA
a(n)=n*A007953(n-1)*A007953(n+1).
EXAMPLE
a(8)=8*ds(7)*ds(9)=8*7*9=504.
a(15)=15*ds(14)*ds(16)=15*5*7=525.
a(26)=26*ds(25)*ds(27)=26*7*9.
MATHEMATICA
Table[n Total[IntegerDigits[n-1]]Total[IntegerDigits[n+1]], {n, 50}] (* Harvey P. Dale, Nov 07 2021 *)
CROSSREFS
Sequence in context: A211615 A195647 A086768 * A160936 A007531 A331433
KEYWORD
nonn,base,easy
AUTHOR
Claudio Meller, May 30 2009
STATUS
approved

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Last modified June 23 00:47 EDT 2024. Contains 373629 sequences. (Running on oeis4.)