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.

Showing 1-7 of 7 results.

A366291 Lexicographically earliest infinite sequence such that a(i) = a(j) => A353271(i) = A353271(j) for all i, j >= 1, where A353271(n) is the numerator of n / A005940(1+(3*A156552(n))).

Original entry on oeis.org

1, 1, 1, 2, 1, 3, 1, 4, 3, 5, 1, 6, 1, 7, 5, 8, 1, 9, 1, 2, 7, 10, 1, 4, 5, 11, 9, 2, 1, 12, 1, 13, 10, 14, 7, 15, 1, 16, 11, 4, 1, 7, 1, 2, 12, 17, 1, 8, 7, 18, 14, 2, 1, 9, 10, 4, 16, 19, 1, 20, 1, 21, 3, 22, 11, 23, 1, 2, 17, 24, 1, 25, 1, 26, 18, 2, 10, 27, 1, 8, 28, 29, 1, 30, 14, 31, 19, 4, 1, 32, 11, 2, 21, 33, 16
Offset: 1

Views

Author

Antti Karttunen, Oct 06 2023

Keywords

Comments

Restricted growth sequence transform of A353271.
For all i, j: A305800(i) = A305800(j) => a(i) = a(j).

Crossrefs

Programs

  • PARI
    up_to = 65537;
    rgs_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), u=1); for(i=1, length(invec), if(mapisdefined(om,invec[i]), my(pp = mapget(om, invec[i])); outvec[i] = outvec[pp] , mapput(om,invec[i],i); outvec[i] = u; u++ )); outvec; };
    
  • 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 };
    A332449(n) = A005940(1+(3*A156552(n)));
    A353271(n) = (n / gcd(n, A332449(n)));
    v366291 = rgs_transform(vector(up_to,n,A353271(n)));
    A366291(n) = v366291[n];

A366292 Dirichlet inverse of A353271, where A353271(n) is the numerator of n / A005940(1+(3*A156552(n))).

Original entry on oeis.org

1, -1, -1, -1, -1, -1, -1, -1, -2, -3, -1, 1, -1, -5, -3, -1, -1, 0, -1, 9, -5, -9, -1, 11, -4, -11, -4, 13, -1, 5, -1, -1, -9, -15, -5, 6, -1, -17, -11, 5, -1, 21, -1, 21, -2, -21, -1, 5, -6, -8, -15, 25, -1, 22, -9, 7, -17, -27, -1, 3, -1, -29, 14, -1, -11, 11, -1, 33, -21, -3, -1, 16, -1, -35, -8, 37, -9, 13
Offset: 1

Views

Author

Antti Karttunen, Oct 06 2023

Keywords

Crossrefs

Cf. A038838 (positions of even terms), A122132 (of odd terms), A353627 (parity of terms).
Cf. also A209635, A342417, A354347, A354823, A359432, A359433, A359577 for other sequences that are equal modulo 2.

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 };
    A332449(n) = A005940(1+(3*A156552(n)));
    A353271(n) = (n / gcd(n, A332449(n)));
    memoA366292 = Map();
    A366292(n) = if(1==n,1,my(v); if(mapisdefined(memoA366292,n,&v), v, v = -sumdiv(n,d,if(dA353271(n/d)*A366292(d),0)); mapput(memoA366292,n,v); (v)));

Formula

a(1) = 1, and for n > 1, a(n) = -Sum_{d|n, dA353271(n/d) * a(d).

A332449 a(n) = A005940(1+(3*A156552(n))).

Original entry on oeis.org

1, 4, 9, 10, 25, 16, 49, 30, 21, 36, 121, 22, 169, 100, 81, 90, 289, 40, 361, 250, 225, 196, 529, 66, 55, 484, 105, 490, 841, 64, 961, 270, 441, 676, 625, 154, 1369, 1156, 1089, 750, 1681, 144, 1849, 1210, 39, 1444, 2209, 198, 91, 84, 1521, 1690, 2809, 120, 1225, 1470, 2601, 2116, 3481, 34, 3721, 3364, 1029, 810, 3025, 400
Offset: 1

Views

Author

Antti Karttunen, Feb 14 2020

Keywords

Crossrefs

Cf. A329609 (terms sorted into ascending order).
Cf. A000290, A003961, A005117 (positions of squares), A005940, A010052, A156552, A277010, A329603, A332450, A332451, A347119, A347120, A353267 [= A348717(a(n))], A353269, A353270 [= gcd(n, a(n))], A353271, A353272, A353273.
Cf. also A332223.

Programs

  • PARI
    A005940(n) = { my(p=2, t=1); n--; until(!n\=2, if((n%2), (t*=p), p=nextprime(p+1))); t }; \\ From A005940
    A156552(n) = {my(f = factor(n), 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}; \\ From A156552
    A332449(n) = A005940(1+(3*A156552(n)));

Formula

a(n) = A005940(1+(3*A156552(n))).
a(p) = p^2 for all primes p.
a(u) = A332451(u) and A010052(a(u)) = 1 for all squarefree numbers (A005117).
a(A003961(n)) = A003961(a(n)) = A005940(1+(6*A156552(n))).
From Antti Karttunen, Apr 10 2022: (Start)
a(n) = A347119(n) * A000290(A347120(n)) = A353270(n) * A353272(n).
a(A353269(n)) = 1 for all n.
(End)

A353270 a(n) = gcd(n, A332449(n)), where A332449(n) = A005940(1+(3*A156552(n))).

Original entry on oeis.org

1, 2, 3, 2, 5, 2, 7, 2, 3, 2, 11, 2, 13, 2, 3, 2, 17, 2, 19, 10, 3, 2, 23, 6, 5, 2, 3, 14, 29, 2, 31, 2, 3, 2, 5, 2, 37, 2, 3, 10, 41, 6, 43, 22, 3, 2, 47, 6, 7, 2, 3, 26, 53, 6, 5, 14, 3, 2, 59, 2, 61, 2, 21, 2, 5, 2, 67, 34, 3, 2, 71, 6, 73, 2, 3, 38, 7, 2, 79, 10, 3, 2, 83, 2, 5, 2, 3, 22, 89, 2, 7, 46, 3, 2, 5, 6
Offset: 1

Views

Author

Antti Karttunen, Apr 09 2022

Keywords

Crossrefs

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 };
    A332449(n) = A005940(1+(3*A156552(n)));
    A353270(n) = gcd(n, A332449(n));

Formula

a(n) = gcd(n, A332449(n)) = gcd(n, A005940(1+(3*A156552(n)))).
a(n) = n / A353271(n) = A332449(n) / A353272(n).

A353272 a(n) = A332449(n) / gcd(n, A332449(n)), where A332449(n) = A005940(1+(3*A156552(n))).

Original entry on oeis.org

1, 2, 3, 5, 5, 8, 7, 15, 7, 18, 11, 11, 13, 50, 27, 45, 17, 20, 19, 25, 75, 98, 23, 11, 11, 242, 35, 35, 29, 32, 31, 135, 147, 338, 125, 77, 37, 578, 363, 75, 41, 24, 43, 55, 13, 722, 47, 33, 13, 42, 507, 65, 53, 20, 245, 105, 867, 1058, 59, 17, 61, 1682, 49, 405, 605, 200, 67, 85, 1083, 162, 71, 77, 73, 1922, 63
Offset: 1

Views

Author

Antti Karttunen, Apr 09 2022

Keywords

Crossrefs

Cf. A005940, A156552, A332449, A353270, A353271, A353273, A353274 [= gcd(n, a(n))].

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 };
    A332449(n) = A005940(1+(3*A156552(n)));
    A353272(n) = { my(u=A332449(n)); (u / gcd(n, u)); };

Formula

a(n) = A332449(n) / A353270(n) = A332449(n) / gcd(n, A332449(n)).
a(p) = p for all primes p.

A353273 a(n) = (A332449(n) / gcd(n, A332449(n))) - n, where A332449(n) = A005940(1+(3*A156552(n))).

Original entry on oeis.org

0, 0, 0, 1, 0, 2, 0, 7, -2, 8, 0, -1, 0, 36, 12, 29, 0, 2, 0, 5, 54, 76, 0, -13, -14, 216, 8, 7, 0, 2, 0, 103, 114, 304, 90, 41, 0, 540, 324, 35, 0, -18, 0, 11, -32, 676, 0, -15, -36, -8, 456, 13, 0, -34, 190, 49, 810, 1000, 0, -43, 0, 1620, -14, 341, 540, 134, 0, 17, 1014, 92, 0, 5, 0, 1848, -12, 19, 266, 314, 0, 145
Offset: 1

Views

Author

Antti Karttunen, Apr 09 2022

Keywords

Crossrefs

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 };
    A332449(n) = A005940(1+(3*A156552(n)));
    A353273(n) = { my(u=A332449(n)); (u / gcd(n, u))-n; };

Formula

a(n) = A353272(n) - n.

A353274 a(n) = gcd(n, A353272(n)).

Original entry on oeis.org

1, 2, 3, 1, 5, 2, 7, 1, 1, 2, 11, 1, 13, 2, 3, 1, 17, 2, 19, 5, 3, 2, 23, 1, 1, 2, 1, 7, 29, 2, 31, 1, 3, 2, 5, 1, 37, 2, 3, 5, 41, 6, 43, 11, 1, 2, 47, 3, 1, 2, 3, 13, 53, 2, 5, 7, 3, 2, 59, 1, 61, 2, 7, 1, 5, 2, 67, 17, 3, 2, 71, 1, 73, 2, 3, 19, 7, 2, 79, 5, 1, 2, 83, 1, 5, 2, 3, 11, 89, 2, 7, 23, 3, 2, 5, 3, 97
Offset: 1

Views

Author

Antti Karttunen, Apr 09 2022

Keywords

Crossrefs

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 };
    A332449(n) = A005940(1+(3*A156552(n)));
    A353274(n) = { my(u=A332449(n)); gcd(n, (u / gcd(n, u))); };

Formula

a(n) = gcd(n, A353272(n)) = gcd(n, A353273(n)) = gcd(A353272(n), A353273(n)).
a(p) = p for all primes p.
Showing 1-7 of 7 results.