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.

A351098 Numbers k such that the maximal digit value in primorial base expansion of the arithmetic derivative of k is less than the maximal exponent in the prime factorization of k.

Original entry on oeis.org

8, 9, 16, 24, 28, 32, 40, 45, 48, 81, 96, 108, 112, 120, 125, 128, 136, 160, 184, 189, 192, 198, 208, 212, 225, 236, 244, 250, 256, 270, 288, 296, 352, 361, 459, 507, 625, 640, 768, 800, 832, 864, 896, 928, 960, 972, 1008, 1024, 1056, 1088, 1104, 1120, 1152, 1168, 1184, 1232, 1272, 1280, 1320, 1344, 1350, 1408, 1440
Offset: 1

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Author

Antti Karttunen, Feb 03 2022

Keywords

Comments

Numbers k such that A328390(k) < A051903(k).
Numbers k for which A051903(A327859(n)) < A051903(k).
These seem to be rarer than A351075. All terms are nonsquarefree.

Crossrefs

Positions of negative terms in A351097. Subsequence of A013929 and of A351099.
Cf. A003415, A051903, A276086, A327859, A328390, A369637 (characteristic function).
Cf. also A351075.

Programs

  • PARI
    A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
    A051903(n) = if((1==n),0,vecmax(factor(n)[, 2]));
    A328114(n) = { my(s=0, p=2); while(n, s = max(s, (n%p)); n = n\p; p = nextprime(1+p)); (s); };
    isA351098(n) = (A328114(A003415(n)) < A051903(n));
    
  • PARI
    \\ Or see A369637.