Group Abstract Group Abstract

Message Boards Message Boards

0
|
307 Views
|
3 Replies
|
0 Total Likes
View groups...
Share
Share this post:

The Wolfram code to compute the sequence A381080(5) ...

Posted 13 days ago
(* a(0)....a(5); a(5) has 19724 decimal digits: *)
a[1, 0, 0] = 1; a[1, 1, 0] = 1; a[1, n_, q_] := 0 /; (q != 0 || (n =!= 0 && n =!= 1)); a[k_Integer?Positive, n_Integer, q_Integer] /; k >= 2 := a[k, n, q] = Sum[Binomial[2^q - 2^(q - m), n] * a[k - 1, m, q - m], {m, 0, q}]; maxq[1] = 0; maxq[k_Integer?Positive] /; 5 >= k >= 2 := maxq[k] = 2^(maxq[k - 1]); aTot[0] = 1; aTotal[k_Integer?Positive] := aTot[k] = Sum[a[k, n, q], {q, 0, maxq[k]}, {n, 0, 2^q}];
Table[aTot[k], {k, 0, 5}] (* or *)
sPrt[mx_, i_, j_] := If[1 <= i <= Length[mx] && 1 <= j <= Length[mx[[i]]], mx[[i, j]], 0]; nxtL[prev_] := Block[{qmax}, qmax = 2^(Length[prev] - 1); Table[ Table[ Sum[ sPrt[prev, q - m + 1, m + 1] * Binomial[2^q - 2^(q - m), n], {m, 0, q}], {n, 0, 2^q}], {q, 0, qmax}]]; aTot[n_] := Prepend[Map[Total[Flatten[#]] &, NestList[nxtL, {{1, 1}}, n]], 1]; Table[aTot[i], {i, 0, 5}] (* _Mikk Heidemaa_, Mar 17 2025 *)
Attachments:
POSTED BY: Mikk Heidemaa
3 Replies
Posted 11 days ago

Abelian orders of hereditarily finite transitive sets.

Sequence: 1, 2, 3, 6, 12, 2^13868 * 3^7873 * 5^2012 * 7^1911, …

Conjecture: a(7) = 2^a ⋅ 3^b ⋅ 5^c ⋅ 7^d ⋅ 11^e ⋅13^f ⋅ ... ⋅ P^z.

Try to prove / disprove... (or to find a(7)...?)

POSTED BY: Mikk Heidemaa
Posted 13 days ago

Would like to know its factors / divisors... ;)

POSTED BY: Mikk Heidemaa
Posted 13 days ago

... a(5) has 19724 decimal digits.

POSTED BY: Mikk Heidemaa
Reply to this discussion
Community posts can be styled and formatted using the Markdown syntax.
Reply Preview
Attachments
Remove
or Discard