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

Author

N. J. A. Sloane, Oct 26 2014

Keywords

• nonn

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

Crossrefs

Cf. A026465, A171946, A171947, A260191.

Programs

Haskell

a249034 n = a249034_list !! (n-1)
a249034_list = filter odd a171946_list
-- Reinhard Zumkeller, Oct 26 2014

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 *)