cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-4 of 4 results.

A083942 Positions of breadth-first-wise encodings (A002542) of the complete binary trees (A084107) in A014486.

Original entry on oeis.org

0, 1, 8, 625, 13402696, 19720133460129649, 126747521841153485025455279433135688, 15141471069096667541622192498608408980462133134430650704600552060872705905
Offset: 0

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Author

Antti Karttunen, May 13 2003

Keywords

Crossrefs

Cf. A014138 (partial sums of Catalan numbers), A000108 (Catalan Numbers).

Formula

a(n) = A057118(A084108(n)).
a(n) = A080300(A002542(n)) [provided that 2^((2^n)-1)*((2^((2^n)-1))-1) is indeed the formula for A002542].
Conjecture: a(n) = A014138(2^n-2) for n>0. - Alexander Adamchuk, Nov 10 2007
Conjecture: a(n) = Sum_{k=1..2^n-1} A000108(k). - Alexander Adamchuk, Nov 10 2007
Let h(n) = -((C(2*n,n)*hypergeom([1,1/2+n],[2+n],4))/(1+n)+I*sqrt(3)/2+1/2). Assuming Adamchuk's conjecture a(n) = h(2^n) and A014138(n) = h(n+1). - Peter Luschny, Mar 09 2015

A084108 A014486-indices of "Complete Binary Trees".

Original entry on oeis.org

0, 1, 6, 477, 11231586, 17656351387745509, 118547604486270210927391203275078974, 14557702344245589436016960628730576845591277100880695377777962217288601549
Offset: 0

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Author

Antti Karttunen, May 13 2003

Keywords

Comments

Fixed points of permutations A069767 and A069768.

Crossrefs

a(n) = A057117(A083942(n)). Also iterates of A080298, i.e., a(1)=A080298(0), a(2)=A080298(A080298(0)), a(3)=A080298(A080298(A080298(0))), etc. Cf. also A083940, A080274.

Formula

a(n) = A080300(A084107(n)).

A356082 Matula-Goebel number of the complete binary tree of n levels.

Original entry on oeis.org

1, 4, 49, 51529, 400034745289, 135016053798647886015597889
Offset: 1

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Author

Kevin Ryde, Jul 26 2022

Keywords

Comments

An estimate for a(7) is 7.304058*10^55. - Hugo Pfoertner, Jul 26 2022

Examples

			For n=3, the complete binary tree of 3 levels is
        49
      /    \     a(3) = prime(4)^2
    4       4         = 49
   / \     / \
  1   1   1   1
		

Crossrefs

Cf. A006894 (Colijn-Plazzotta), A084107 (balanced binary).
Cf. A356083 (ternary), A356084 (quaternary).

Programs

  • PARI
    a(n) = my(ret=1); for(i=2,n, ret=prime(ret)^2); ret;

Formula

a(n) = prime(a(n-1))^2, for n>=2.

Extensions

a(6) from Rémy Sigrist, Jul 26 2022

A083941 A014486-encoding of symmetric binary trees.

Original entry on oeis.org

0, 2, 50, 844, 906, 13624, 13876, 14642, 14892, 15402, 218352, 219368, 222436, 223448, 225492, 234722, 235730, 238796, 239800, 241844, 246986, 247986, 250028, 254122, 3494880, 3498960, 3511240, 3515312, 3523496, 3560388, 3564452, 3576728
Offset: 0

Views

Author

Antti Karttunen, May 13 2003

Keywords

Crossrefs

Subsets: A084107, A080263, A080293.

Formula

a(n) = A014486(A083940(n)).
Showing 1-4 of 4 results.