A249034 Odd numbers missing from A171947.

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

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: A375937 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