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.

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A342654 a(n) = A005940(1+A324104(n)); Euler totient phi conjugated by A156552.

Original entry on oeis.org

1, 2, 2, 3, 3, 5, 5, 9, 3, 9, 7, 15, 11, 11, 5, 7, 13, 25, 17, 21, 9, 35, 19, 45, 5, 121, 9, 49, 23, 25, 29, 81, 11, 385, 7, 21, 31, 23, 35, 49, 37, 55, 41, 39, 15, 1105, 43, 135, 7, 35, 121, 51, 47, 125, 25, 99, 385, 4693, 53, 105, 59, 85085, 21, 55, 13, 175, 61, 5929, 23, 77, 67, 77, 71, 279841, 25, 8281, 11, 1225
Offset: 1

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Author

Antti Karttunen, Mar 18 2021

Keywords

Crossrefs

Cf. also A332223 (sigma similarly conjugated).

Programs

  • PARI
    A005940(n) = { my(p=2, t=1); n--; until(!n\=2, if((n%2), (t*=p), p=nextprime(p+1))); (t); };
    A156552(n) = {my(f = factor(n), p, p2 = 1, res = 0); for(i = 1, #f~, p = 1 << (primepi(f[i, 1]) - 1); res += (p * p2 * (2^(f[i, 2]) - 1)); p2 <<= f[i, 2]); res};
    A324104(n) = if(1==n,0,eulerphi(A156552(n)));
    A342654(n) = A005940(1+A324104(n));

Formula

a(1) = 1, and for n > 1, a(n) = A005940(1+A000010(A156552(n))).
a(n) = A005940(1+A324104(n)).
For n >= 2, a(A000040(n)) = A000040(n-1).
Previous Showing 11-11 of 11 results.