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A032945
Numbers k whose base-10 representation Sum_{i=0..m} d(i)*10^(m-i) has d(i)=0 for all odd i. Here m is the position of the lead digit of k.
4
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 300, 301, 302, 303, 304, 305, 306, 307, 308, 309, 400, 401, 402, 403
OFFSET
1,3
COMMENTS
Every nonnegative integer can be represented as the sum of two members of this sequence. - Franklin T. Adams-Watters, Aug 30 2014
This first differs from A236402 at a(110)=1000 (followed by 1010, 1020, 1030, ...), while A236402(110)=910 (followed by 1000, 1001, 1002, ...). - M. F. Hasler, Dec 28 2014
LINKS
MAPLE
N:= 6: # to get all terms with up to N digits
A[1]:= 0:
count:= 1:
for d from 1 to N do
dp:= ceil(d/2);
for j from 10^(dp-1) to 10^dp-1 do
L:= ListTools[Reverse](convert(j, base, 10));
L:= ListTools[Interleave](L, [0$(d-dp)]);
count:= count+1;
A[count]:= add(L[i]*10^(d-i), i=1..d);
od
od:
seq(A[i], i=1..count); # Robert Israel, Aug 31 2014
PROG
(PARI) is(n)=!forstep(i=2, #n=digits(n), 2, n[i]&&return) \\ M. F. Hasler, Dec 28 2014
(Python)
def ok(n): return str(n)[1::2].strip('0') == ""
print([k for k in range(404) if ok(k)]) # Michael S. Branicky, Apr 12 2022
CROSSREFS
Cf. A126684.
Sequence in context: A107085 A212499 A244890 * A236402 A052018 A352461
KEYWORD
nonn,base
EXTENSIONS
Definition corrected by Franklin T. Adams-Watters, Aug 30 2014
STATUS
approved