OFFSET
1,1
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..10000
MATHEMATICA
Join[{4}, FromDigits[#, 7]&/@Select[Flatten[Table[Join[{4}, #, {4}]&/@ Tuples[ Range[ 0, 6], n], {n, 0, 3}], 1], #==Reverse[#]&]] (* Harvey P. Dale, Sep 13 2020 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
STATUS
approved