A372290 Numbers that occur in the odd bisection of A371094.

21, 45, 69, 93, 117, 141, 165, 189, 213, 237, 261, 285, 309, 333, 341, 357, 381, 405, 429, 453, 477, 501, 525, 549, 573, 597, 621, 645, 669, 693, 717, 725, 741, 765, 789, 813, 837, 861, 885, 909, 933, 957, 981, 1005, 1029, 1053, 1077, 1101, 1109, 1125, 1149, 1173, 1197, 1221, 1245, 1269, 1293, 1317, 1341, 1365, 1389

Offset

1,1

Comments

Numbers that occur in array A371100.

Links

Antti Karttunen, Table of n, a(n) for n = 1..62122

Example

21 is present because A371094(1) = A371094(3) = 21.
45 is present because A371094(7) = 45.
87381 is present because A371094(85) = A371094(213) = A371094(7281) = A371094(14563) = 87381.

Prog

(PARI)
A371094(n) = { my(m=1+3*n, e=valuation(m, 2)); ((m*(2^e)) + (((4^e)-1)/3)); };
isA372290(n) = if(!(n%2), 0, forstep(k=1, n, 2, if(A371094(k)==n, return(1))); (0));
(PARI)
A371094(n) = { my(m=1+3*n, e=valuation(m, 2)); ((m*(2^e)) + (((4^e)-1)/3)); };
A372290list(up_to_n) = { my(v=vector((1+up_to_n)/2), x, lista=List([])); forstep(k=1, up_to_n, 2, x=A371094(k); if(x <= up_to_n, v[(x+1)/2]++)); for(i=1, (1+up_to_n)/2, if(v[i]>0, listput(lista, i+i-1))); Vec(lista); };

Crossrefs

Union of A372291 and A372292.

Cf. A102603 (subsequence), A371094, A371100.

Sequence in context: A317210 A099468 A063500 * A102603 A147222 A199767

Adjacent sequences: A372287 A372288 A372289 * A372291 A372292 A372293

Keyword

nonn

Author

Antti Karttunen, Apr 26 2024

Status

approved