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A243097
Digit sums of the nontrivial reversal numbers (numbers which are integer multiples of their reversal), excluding palindromes and multiples of 10.
1
18, 18, 27, 27, 36, 36, 45, 45, 36, 54, 36, 54, 36, 63, 36, 63, 36, 54, 72, 36, 54, 72, 36, 54, 81, 36, 54, 81, 36, 54, 54, 72, 90, 36, 54, 54, 72, 90, 36, 63, 54, 72, 99, 36, 63, 54, 72, 99, 36, 54, 72, 54, 72, 72, 90, 108, 36, 54, 72, 54, 72, 72, 90, 108
OFFSET
1,1
FORMULA
a(n) = 9(d-2p-b) where d is the number of digits in the reversal number, p is the number of repeating units of either 8712 or 9801 (they can be split in the middle of the sequence as long as all 4 numbers appear in the correct order), and b is the number of digits separating two complete "units" (must appear between two complete units and not in between 1 incomplete unit).
a(n) = A007953(A031877(n)).
EXAMPLE
a(1)=digit sum of 8712=8+7+1+2=18, a(3)=digit sum of 87912=8+7+9+1+2=27.
PROG
(Python)
A243097 = []
for n in range(1, 10**7):
....if n % 10:
........s1 = str(n)
........s2 = s1[::-1]
........if s1 != s2 and not n % int(s2):
............A243097.append(sum(int(d) for d in s1))
# Chai Wah Wu, Sep 05 2014
CROSSREFS
Cf. A007953 (digit sum), A031877 (union of A222814 and A222815).
Sequence in context: A010857 A369860 A158910 * A040307 A022352 A211411
KEYWORD
nonn,base
AUTHOR
Sam Mathers, Aug 18 2014
EXTENSIONS
More terms from Michel Marcus, Aug 25 2014
STATUS
approved