login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A262901 Numbers that have at least one leaf-child in the tree generated by edge-relation A049820(child) = parent. 7

%I

%S 4,5,11,14,16,17,22,27,29,32,35,41,44,46,48,51,57,58,62,65,69,70,77,

%T 80,81,91,92,96,101,102,107,110,111,114,118,119,120,128,129,130,138,

%U 139,141,144,147,148,152,155,158,161,162,165,166,169,176,181,187,191,192,199,201,214,215,216,222,224,227,231,234,238,239,247,248,249,255,258,262,264,269,277,278,282,286,291,294,296

%N Numbers that have at least one leaf-child in the tree generated by edge-relation A049820(child) = parent.

%C Positions of nonzeros in A262900.

%C Numbers n such that there is at least one k such that k - d(k) = n [where d(k) is the number of divisors of k, A000005(k)], but there is no such x that x - d(x) = k, in other words, k is one of the terms of A045765.

%C Sequence A262902 sorted into ascending order, with duplicates removed.

%H Antti Karttunen, <a href="/A262901/b262901.txt">Table of n, a(n) for n = 1..10000</a>

%o (Scheme, with _Antti Karttunen_'s IntSeq-library)

%o (define A262901 (NONZERO-POS 1 0 A262900))

%Y Cf. A000005, A045765, A049820, A262900, A262902.

%Y Cf. A262903 (a subsequence).

%Y Subsequence of A236562.

%Y Cf. also A257508.

%K nonn

%O 1,1

%A _Antti Karttunen_, Oct 06 2015

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 18 19:04 EDT 2021. Contains 345120 sequences. (Running on oeis4.)