A352439 Numbers k whose decimal expansion ends in the sum of the first two digits of k.

101, 112, 123, 134, 145, 156, 167, 178, 189, 202, 213, 224, 235, 246, 257, 268, 279, 303, 314, 325, 336, 347, 358, 369, 404, 415, 426, 437, 448, 459, 505, 516, 527, 538, 549, 606, 617, 628, 639, 707, 718, 729, 808, 819, 909, 910, 1001, 1011, 1021, 1031, 1041, 1051, 1061, 1071, 1081, 1091, 1102, 1112, 1122, 1132

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Example

   101 is a term because  "101" ends in "1" = 1 + 0;
   112 is a term because  "112" ends in "2" = 1 + 1;
  1132 is a term because "1132" ends in "2" = 1 + 1; etc.

Maple

S[3]:= [seq(seq(100*i + 10*j + (i+j), j=0..9-i), i=1..9), 910];
g:= proc(t, k) local a, b, j;
     b:= t mod 10;
     a:= (t-b)/10;
     seq(a*10^(k+1) + 10*j + b, j=0..10^k-1)
end proc:
S[4]:= map(g, S[3], 1):
map(op, [S[3], S[4]]); # Robert Israel, Jan 13 2026

Mathematica

q[n_] := Module[{d = IntegerDigits[n], s, ds, nds}, s = Plus @@ d[[1 ;; 2]]; ds = IntegerDigits[s]; nds = Length[ds]; ds == d[[-nds ;; -1]]]; Select[Range[10, 1140], q] (* Amiram Eldar, Mar 16 2022 *)
Select[Range[100, 1200], Total[Take[IntegerDigits[#], 2]]==Mod[#, 10]||Total[Take[IntegerDigits[#], 2]]==Mod[#, 100]&] (* Harvey P. Dale, Mar 29 2024 *)

Prog

(Python)
def ok(n):
    s = str(n)
    return n > 9 and s.endswith(str(int(s[0])+int(s[1])))
print([k for k in range(1140) if ok(k)]) # Michael S. Branicky, Mar 16 2022

Crossrefs

Cf. A352438.

Sequence in context: A284404 A267585 A294743 * A214527 A084413 A248533

Adjacent sequences: A352436 A352437 A352438 * A352440 A352441 A352442

Keyword

base,nonn

Author

Eric Angelini and Carole Dubois, Mar 16 2022

Status

approved