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.

A322991 a(n) = A289272(2*A289271(n)).

Original entry on oeis.org

1, 3, 4, 5, 7, 12, 8, 9, 11, 15, 13, 20, 16, 21, 28, 17, 19, 24, 23, 35, 36, 33, 25, 44, 27, 39, 29, 40, 31, 60, 32, 37, 52, 48, 56, 45, 41, 51, 68, 63, 43, 84, 47, 55, 77, 57, 49, 76, 53, 69, 92, 65, 59, 75, 91, 72, 100, 87, 61, 140, 64, 93, 88, 67, 112, 132, 71, 80, 108, 105, 73, 99, 79, 96, 116, 85, 104, 156, 81, 119, 83, 111, 89
Offset: 1

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Author

Antti Karttunen, Jan 01 2019

Keywords

Crossrefs

Permutation of A042965 (apart from zero).
Cf. also A003963, A300841.

Programs

  • PARI
    A289271(n) = { my(v=0,i=0,x=1); for(d=2,oo,if(n==1, return(v)); if(1==gcd(x,d)&&1==omega(d), if(!(n%d)&&1==gcd(d,n/d), v += 2^i; n /= d; x *= d); i++)); }; \\ After Rémy Sigrist's program for A289271.
    A289272(n) = { my(m=1, pp=1); while(n>0, pp++; while(!isprimepower(pp)||(gcd(pp,m)>1), pp++); if(n%2, m *= pp); n >>=1); (m); };
    A322991(n) = A289272(2*A289271(n));

Formula

a(n) = A289272(2*A289271(n)).