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 1-3 of 3 results.

A258008 First differences of A231718.

Original entry on oeis.org

7, 6, 4, 4, 11, 4, 4, 4, 8, 4, 4, 10, 4, 12, 29, 4, 4, 4, 8, 4, 4, 10, 4, 12, 38, 4, 4, 10, 4, 12, 47, 4, 12, 57, 182, 4, 4, 4, 8, 4, 4, 10, 4, 12, 38, 4, 4, 10, 4, 12, 47, 4, 12, 57, 231, 4, 4, 10, 4, 12, 47, 4, 12, 57, 277, 4, 12, 57, 322, 359, 335, 314, 222, 31, 35
Offset: 1

Views

Author

Antti Karttunen, Jun 05 2015

Keywords

Crossrefs

Programs

Formula

a(n) = A231718(n+1) - A231718(n).

A231717 After a(0)=0, a(n) = A231713(A219666(n),A219666(n-1)).

Original entry on oeis.org

0, 1, 2, 2, 3, 3, 3, 3, 1, 6, 3, 3, 3, 2, 1, 6, 2, 3, 1, 3, 5, 3, 1, 3, 6, 2, 2, 3, 10, 3, 3, 3, 2, 1, 6, 2, 3, 1, 3, 5, 3, 1, 3, 6, 2, 1, 3, 5, 5, 3, 10, 2, 3, 1, 3, 5, 3, 1, 3, 6, 2, 1, 2, 4, 2, 4, 5, 3, 3, 9, 3, 1, 3, 6, 2, 1, 2, 4, 2, 4, 5, 3, 2, 4, 3, 10
Offset: 0

Views

Author

Antti Karttunen, Nov 12 2013

Keywords

Comments

For all n, a(A226061(n+1)) = A232095(n). This works because at the positions given by each x=A226061(n+1), it holds that A219666(x) = (n+1)!-1, which has a factorial base representation (A007623) of (n,n-1,n-2,...,3,2,1) whose digit sum (A034968) is the n-th triangular number, A000217(n). This in turn is always a new record as at those points, in each significant digit position so far employed, a maximal digit value (for factorial number system) is used, and thus the preceding term, A219666(x-1) cannot have any larger digits in its factorial base representation, and so the differences between their digits (in matching positions) are all nonnegative.

Crossrefs

A231718 gives the positions of ones.
Cf. also A230410, A231719, A232095.

Programs

Formula

a(0)=0, and for n>=1, a(n) = A231713(A219666(n),A219666(n-1)).

A230422 Positions of ones in A230410.

Original entry on oeis.org

1, 8, 14, 16, 18, 22, 33, 35, 37, 41, 45, 51, 53, 57, 61, 71, 75, 82, 87, 96, 106, 116, 118, 120, 124, 128, 134, 136, 140, 144, 154, 158, 165, 170, 179, 189, 198, 200, 206, 208, 212, 216, 226, 230, 237, 242, 251, 261, 270, 272, 280, 289, 293, 300, 305, 314, 324
Offset: 1

Views

Author

Antti Karttunen, Nov 10 2013

Keywords

Comments

This sequence gives all n at which positions the successive terms A219666(n-1) & A219666(n) in the infinite trunk of the factorial beanstalk differ only in one digit position in their factorial base representations (A007623).
Please see further comments and examples in A230410.

Examples

			14 is included, because A219666(13) = 40 = '1220' in factorial base representation, while A219666(14) = 46 = '1320' in factorial base, and they differ only by their third least significant digit.
16 is included, because A219666(15) = 48 = '2000' in factorial base representation, while A219666(16) = 52 = '2020' in factorial base, and they differ only by their second least significant digit.
		

Crossrefs

Subset: A231718. Cf. also A230410 and A258010 (first differences).

Programs

  • Mathematica
    nn = 10^4; m = 1; While[m! < Floor[6 nn/5], m++]; m; f[n_] := IntegerDigits[n, MixedRadix[Reverse@ Range[2, m]]]; Position[#, 1] &[Function[w, Count[Subtract @@ Map[PadLeft[#, Max@ Map[Length, w]] &, w], k_ /; k != 0]]@ Map[f@ # &, {#1, #2}] & @@@ Partition[#, 2, 1] &@ TakeWhile[Reverse@ NestWhileList[# - Total@ f@ # &, Floor[6 nn/5], # > 0 &], # <= nn &]] // Flatten (* Michael De Vlieger, Jun 27 2016, Version 10.2 *)

Formula

For all n, A230406(a(n)) is one of the terms of A051683.
Showing 1-3 of 3 results.