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A061472
First (leftmost) digit - second digit + third digit - fourth digit .... = 3.
2
3, 30, 41, 52, 63, 74, 85, 96, 102, 113, 124, 135, 146, 157, 168, 179, 201, 212, 223, 234, 245, 256, 267, 278, 289, 300, 311, 322, 333, 344, 355, 366, 377, 388, 399, 410, 421, 432, 443, 454, 465, 476, 487, 498, 520, 531, 542, 553, 564, 575, 586, 597, 630
OFFSET
1,1
LINKS
FORMULA
A225693(n) = 3. - Robert Israel, Jun 12 2019
EXAMPLE
124 is in the sequence since 1 - 2 + 4 = 3.
MAPLE
A225693:= proc(n) local L, m, i;
L:= convert(n, base, 10);
m:= nops(L);
add(L[i]*(-1)^(m-i), i=1..m);
end proc:
select(A225693=3, [$1..1000]); # Robert Israel, Jun 12 2019
MATHEMATICA
aQ[n_] := Differences[Total @ Take[IntegerDigits[n], {#, -1, 2}] & /@ {2, 1}][[1]] == 3; Select[Range[1000], aQ] (* Amiram Eldar, Jun 12 2019 *)
Select[Range[1000], Total[Times@@@Partition[Riffle[IntegerDigits[#], {1, -1}, {2, -1, 2}], 2]]==3&] (* Harvey P. Dale, May 16 2020 *)
PROG
(PARI) isok(n) = my(d=digits(n)); sum(k=1, #d, (-1)^(k+1)*d[k]) == 3; \\ Michel Marcus, Jun 12 2019
KEYWORD
nonn,base,easy
AUTHOR
Amarnath Murthy, May 05 2001
EXTENSIONS
More terms from Robert G. Wilson v, May 10 2001 and from Larry Reeves (larryr(AT)acm.org), May 14 2001
STATUS
approved