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A167996
Positive numbers n with property that first digit of 3*n = last digit of n.
7
13, 14, 28, 41, 51, 61, 72, 82, 92, 103, 113, 123, 133, 134, 144, 154, 164, 175, 185, 195, 206, 216, 226, 237, 247, 257, 268, 278, 288, 298, 309, 319, 329, 341, 351, 361, 371, 381, 391, 401, 411, 421, 431, 441, 451, 461, 471, 481, 491, 501, 511, 521, 531, 541, 551, 561, 571, 581
OFFSET
1,1
LINKS
FORMULA
A000030(A008585(a(n))) = A010879(a(n)). (Defining property of the terms of this sequence.) - M. F. Hasler, Apr 22 2024
EXAMPLE
3*13=39, 3*14=42, 3*28=84, 3*41=123, etc.
MATHEMATICA
Reap[Do[If[IntegerDigits[n][[ -1]]==IntegerDigits[3*n][[1]], Sow[n]], {n, 1000}]][[2, 1]]
Select[Range[600], Last[IntegerDigits[#]]==First[IntegerDigits[3#]]&] (* Harvey P. Dale, Jul 10 2013 *)
PROG
(PARI) select( {is_A167996(n)=n*3\10^logint(3*n+!n, 10)==n%10}, [1..666]) \\ M. F. Hasler, Apr 22 2024
(Python) is_A167996 = lambda x: int(str(3*x)[0]) == x % 10 # M. F. Hasler, Apr 22 2024
CROSSREFS
Cf. A000030 (first digit of n), A010879 (last digit of n), A008585 (3*n).
Cf. A167994.
Sequence in context: A041340 A041338 A042411 * A308122 A292116 A071870
KEYWORD
base,nonn
AUTHOR
Zak Seidov, Nov 16 2009
STATUS
approved