The On-Line Encyclopedia of Integer Sequences (OEIS)

A361505 revision #14

A361505

Index of 2^n in A359804.

1, 2, 5, 10, 24, 38, 87, 172, 349, 706, 1407, 2752, 5487, 11103, 22285, 44429, 88993, 177746, 356460, 712129, 1425163, 2849424, 5701776, 11401709, 22804522, 45608572, 91219022, 182438457

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OFFSET

0,2

LINKS

Table of n, a(n) for n=0..27.

MATHEMATICA

nn = 2^20; c[_] = False; q[_] = 1;

i = 1; j = 2; c[1] = c[2] = True; u = 3;

{1, 2}~Join~Reap[Monitor[Do[

(k = q[#]; While[c[k #], k++]; k *= #;

While[c[# q[#]], q[#]++]) &[(p = 2;

While[Divisible[i j, p], p = NextPrime[p]]; p)];

If[IntegerQ@ Log2[k], Sow[n]];

Set[{c[k], i, j}, {True, j, k}];

If[k == u, While[c[u], u++]], {n, 3, nn}], n]][[-1, -1]] (* Michael De Vlieger, Mar 18 2023 *)

CROSSREFS

Cf. A359804, A361502, A361504.

Sequence in context: A152784 A375995 A112855 * * A299436 A049937

Adjacent sequences: A361502 A361503 A361504 * A361506 A361507 A361508

KEYWORD

nonn,more,new

AUTHOR

N. J. A. Sloane, Mar 18 2023

EXTENSIONS

a(26)-a(27) from Michael De Vlieger, Mar 19 2023

STATUS

approved