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A249034 Odd numbers missing from A171947. 4
5, 13, 17, 21, 29, 37, 45, 49, 53, 61, 65, 69, 77, 81, 85, 93, 101, 109, 113, 117, 125, 133, 141, 145, 149, 157, 165, 173, 177, 181, 189, 193, 197, 205, 209, 213, 221, 229, 237, 241, 245, 253, 257, 261, 269, 273, 277, 285, 293, 301, 305, 309, 317, 321, 325 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

These are the odd terms in A171946.

Consider the sequence of first differences, divided by 4: 2, 1, 1, 2, 2, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 2, 2, 1, 1, 2, 2, 2, ... This is, almost certainly, A026465 without its leading 1. - N. J. A. Sloane, Oct 30 2014

This sequence appears to be the same as A260191, Numbers n such that there exists no square whose base-n digit sum is binomial(n,2), without that sequence's leading 3. - Jon E. Schoenfield, Jul 19 2015

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

MATHEMATICA

f[n_] := Block[{a = {1}, b = {}, k}, Do[k = 2; While[MemberQ[a, k] || MemberQ[b, k], k++]; AppendTo[a, 2 k - 1]; AppendTo[b, k], {i, 2, n}]; a]; Complement[Range[1, Max@ #, 2], #] &@ f@ 120 (* Michael De Vlieger, Jul 20 2015 *)

PROG

(Haskell)

a249034 n = a249034_list !! (n-1)

a249034_list = filter odd a171946_list

-- Reinhard Zumkeller, Oct 26 2014

CROSSREFS

Cf. A026465, A171946, A171947, A260191.

Sequence in context: A039955 A213340 A014539 * A208883 A182078 A074278

Adjacent sequences:  A249031 A249032 A249033 * A249035 A249036 A249037

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Oct 26 2014

STATUS

approved

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Last modified October 16 06:05 EDT 2019. Contains 328046 sequences. (Running on oeis4.)