A372351 - OEIS

%I #13 Apr 29 2024 15:45:19

%S 21,21,341,45,117,69,341,93,213,117,5461,141,309,165,725,189,405,213,

%T 1877,237,501,261,1109,285,597,309,5461,333,693,357,1493,381,789,405,

%U 3413,429,885,453,1877,477,981,501,87381,525,1077,549,2261,573,1173,597,4949,621,1269,645,2645,669,1365,693,11605,717

%N Odd bisection of A371094.

%F a(n) = A371094(2*n-1).

%t Table[With[{e = IntegerExponent[6*n - 2, 2]}, (6*n - 2)*2^e + (4^e - 1)/3], {n, 100}] (* _Paolo Xausa_, Apr 29 2024 *)

%o (PARI)

%o A371094(n) = { my(m=1+3*n, e=valuation(m,2)); ((m*(2^e)) + (((4^e)-1)/3)); };

%o A372351(n) = A371094(n+n-1);

%o (Python)

%o def A372351(n): return ((m:=6*n-2)<<(e:=(~m & m-1).bit_length()))+((1<<(e<<1))-1)//3 # _Chai Wah Wu_, Apr 28 2024

%Y Row 2 of A372282.

%Y Cf. A371094, and array A371100 (gives the same terms, in different order).

%Y Cf. A372290 (the range of this sequence), A372291 (numbers that occur only once), A372292 (more than once), A372293 (odd numbers not occurring here).

%K nonn

%O 1,1

%A _Antti Karttunen_, Apr 28 2024