A392980 Positions of zeros in A393336.

4, 9, 75, 76, 82, 97, 143, 150, 153, 165, 168, 195, 196, 1119, 1134, 1141, 1144, 1182, 1197, 1203, 1204, 1227, 1228, 1234, 1249, 1309, 1323, 1324, 1330, 1351, 1354, 1361, 1376, 1414, 1417, 1424, 1563, 1564, 1575, 1578, 1585, 1606, 1609, 1616, 1669, 1672, 1795, 1796, 2174

Offset

1,1

Comments

The number of bits in each term is 0 or -1 (mod 4). - Ruud H.G. van Tol, Feb 28 2026

Links

Paolo Xausa, Table of n, a(n) for n = 1..10000

Formula

a(n) = A392236(2*n)/2.

Mathematica

A392980Q[k_] := Total[#*Range[Length[#], 1, -1]] == 0 & [2*IntegerDigits[k, 2] - 1];
Select[Range[2500], A392980Q]

Prog

(PARI) lista(len) = len<1 && return([]); my(r=List(), b); for(i=1, oo, #(b=binary(i))%4%3 && (i+=2^(#b-1)-1) && next; if(!(2*b*-[-#b..-1]~ - binomial(#b+1, 2)), listput(~r, i); #r<len||break)); Vec(r); \\ Ruud H.G. van Tol, Mar 02 2026
(Python)
from itertools import count, islice
def A392980_gen(startvalue=1): # generator of terms >= startvalue
    return filter(lambda n: not (m:=n.bit_length()+1)&2 and (sum(i if j == '1' else 0 for i, j in enumerate(bin(n)[:1:-1], 1))<<2)==m*(m-1), count(max(startvalue, 1)))
A392980_list = list(islice(A392980_gen(), 40)) # Chai Wah Wu, Mar 07 2026

Crossrefs

Cf. A058377, A392236, A393336.

Sequence in context: A041777 A367276 A100517 * A327579 A041597 A041030

Adjacent sequences: A392977 A392978 A392979 * A392981 A392982 A392984

Keyword

nonn,base

Author

Paolo Xausa, Feb 26 2026

Status

approved