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.

A354194 Numbers k for which phi(A267099(k)) is equal to phi(k), but the number of 4m+1 and 4m+3 primes in the prime factorization of k (when counted with multiplicity) is not equal. Here A267099 is fully multiplicative involution swapping the positions of 4m+1 and 4m+3 primes, and phi is Euler totient function.

Original entry on oeis.org

69037, 70807, 76635, 79577, 81631, 82425, 88335, 95025, 138074, 141614, 149209, 153270, 153703, 159154, 163262, 164850, 171989, 176670, 177199, 190050, 276148, 283228, 298418, 306540, 307406, 318308, 326524, 329700, 343978, 353340, 354398, 380100, 552296, 566456, 596836, 613080, 614812, 636616, 653048, 659400, 687956
Offset: 1

Views

Author

Antti Karttunen, May 20 2022

Keywords

Examples

			A354102(69037) = phi(A267099(69037)) = phi(70807) = phi(69037) = 62400, and 69037 = 17*31*131, therefore 69037 is included in this sequence, and likewise is 70807 = 11*41*157.
		

Crossrefs

Setwise difference A354189 \ A072202.

Programs

  • PARI
    A354188(n) = (eulerphi(A267099(n)) == eulerphi(n)); \\ Uses the program given in A267099.
    A342025(n) = {my(f = factor(n)); sum(k=1, #f~, ((f[k, 1] % 4)==1)*f[k, 2]) == sum(k=1, #f~, ((f[k, 1] % 4)==3)*f[k, 2]); }; \\ From isok function in A072202
    isA354194(n) = (A354188(n) && !A342025(n));