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 A171757 Even numbers whose binary expansion begins 10. 9
 2, 4, 8, 10, 16, 18, 20, 22, 32, 34, 36, 38, 40, 42, 44, 46, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 128, 130, 132, 134, 136, 138, 140, 142, 144, 146, 148, 150, 152, 154, 156, 158, 160, 162, 164, 166, 168, 170, 172, 174, 176, 178 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..1024 from R. J. Mathar) FORMULA a(n) = 2*A004761(n+1). - Jon Maiga / Georg Fischer, Jun 24 2021 MAPLE n := 1 ; for k from 2 to 4000 by 2 do dgs := convert(k, base, 2) ; if op(-1, dgs) = 1 and op(-2, dgs) = 0 then printf("%d %d\n", n, k) ; n := n+1 ; end if; end do: # R. J. Mathar, Jan 31 2015 MATHEMATICA Select[Range[2, 200, 2], IntegerDigits[#, 2][[1 ;; 2]] == {1, 0} &] (* Amiram Eldar, Sep 01 2020 *) PROG (Python) from itertools import count, product, takewhile def agen(): # generator for sequence yield 2 for digits in count(0): for mid in product("01", repeat=digits): yield int("10" + "".join(mid) + "0", 2) def aupto(lim): return list(takewhile(lambda x: x <= lim, agen())) print(aupto(180)) # Michael S. Branicky, Jun 24 2021 (PARI) isok(m) = if (!(m%2), my(b=binary(m)); (b[1]==1) && (b[2]==0)); \\ Michel Marcus, Jun 24 2021 CROSSREFS Cf. A004761, A171758, A171763, A171764. A subsequence of A004754. Sequence in context: A076919 A336659 A341655 * A350780 A128106 A354776 Adjacent sequences: A171754 A171755 A171756 * A171758 A171759 A171760 KEYWORD nonn,base AUTHOR N. J. A. Sloane, Oct 12 2010 STATUS approved

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Last modified March 31 18:36 EDT 2023. Contains 361672 sequences. (Running on oeis4.)