OFFSET
1,1
COMMENTS
Includes A000217(2*10^k + 1) and A000217(2*10^k + 2) for k >= 1, A000217(10^k), A000217(10^k + 1), A000217(12*10^i + 9), A000217(12*10^i + 12) and A000217(4*10^(2*i) + 6*10^i + 3) for k >= 2, and A000217(4*10^k + 51), A00217(4*10^k + 63) and A000217(14*10^k + 14) for k >= 3. - Robert Israel, Oct 30 2024
LINKS
Robert Israel, Table of n, a(n) for n = 1..295 (first 203 terms from Harvey P. Dale)
EXAMPLE
4095 is a term: 4 + 5 = 9 = 0 + 9.
MAPLE
a:=proc(n) local nn: nn:=convert(n*(n+1)/2, base, 10): if sum(nn[j], j=2..nops(nn)-1)=nn[1]+nn[nops(nn)] then n*(n+1)/2 else fi end: seq(a(n), n=1..1300); # Emeric Deutsch, Aug 06 2005
MATHEMATICA
Do[d = IntegerDigits[n*(n+1)/2]; l = Length[d]; s = d[[1]] + d[[l]]; If[Plus @@ d == 2*s, Print[n*(n+1)/2]], {n, 1, 10^3}] (* Ryan Propper, Aug 06 2005 *)
edidQ[n_]:=Module[{idn=IntegerDigits[n]}, Total[idn[[1]]+idn[[-1]]]== Total[ Most[ Rest[idn]]]]; Select[Accumulate[Range[2000]], edidQ]//Quiet (* Harvey P. Dale, Nov 23 2022 *)
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Amarnath Murthy, Sep 29 2003
EXTENSIONS
Offset changed by Andrew Howroyd, Sep 21 2024
STATUS
approved