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A015977
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Two iterations of Reverse and Add are needed to reach a palindrome.
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2
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5, 6, 7, 8, 9, 19, 28, 37, 39, 46, 48, 49, 55, 57, 58, 64, 66, 67, 73, 75, 76, 82, 84, 85, 91, 93, 94, 109, 119, 129, 139, 149, 150, 151, 152, 153, 154, 159, 160, 161, 162, 163, 169, 170, 171, 172, 173, 179, 189, 208, 218, 219, 228, 229, 238, 239, 248
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OFFSET
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0,1
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COMMENTS
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The number of iterations starts at 1, so palindromes (cf. A002113) are not excluded. The corresponding sequence excluding palindromes is A065207.
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LINKS
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MATHEMATICA
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Select[Range[250], Boole[PalindromeQ/@Rest[NestList[#+IntegerReverse[#]&, #, 2]]] == {0, 1}&] (* Harvey P. Dale, May 11 2022 *)
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PROG
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(Python)
def ra(n): s = str(n); return int(s) + int(s[::-1])
def ispal(n): s = str(n); return s == s[::-1]
def aupto(limit):
alst = []
for k in range(limit+1):
k2 = ra(k)
if ispal(k2): continue
if ispal(ra(k2)): alst.append(k)
return alst
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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