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 1-3 of 3 results.

A278254 Least number with the prime signature of n^2; square of the least number with the prime signature of n.

Original entry on oeis.org

1, 4, 4, 16, 4, 36, 4, 64, 16, 36, 4, 144, 4, 36, 36, 256, 4, 144, 4, 144, 36, 36, 4, 576, 16, 36, 64, 144, 4, 900, 4, 1024, 36, 36, 36, 1296, 4, 36, 36, 576, 4, 900, 4, 144, 144, 36, 4, 2304, 16, 144, 36, 144, 4, 576, 36, 576, 36, 36, 4, 3600, 4, 36, 144, 4096, 36, 900, 4, 144, 36, 900, 4, 5184, 4, 36, 144, 144, 36, 900, 4, 2304, 256, 36, 4, 3600, 36, 36, 36
Offset: 1

Views

Author

Antti Karttunen, Nov 19 2016

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Times @@ MapIndexed[(Prime@ First@ #2)^#1 &, #] &@ If[Length@ # == 1 && #[[1, 1]] == 1, {0}, Reverse@ Sort@ #[[All, -1]]] &@ FactorInteger[ n^2], {n, 120}] (* Michael De Vlieger, Nov 21 2016 *)
  • PARI
    a(n)=my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i])^2 \\ Charles R Greathouse IV, Feb 03 2017
  • Scheme
    (define (A278254 n) (A000290 (A046523 n)))
    (define (A278254 n) (A046523 (A000290 n)))
    

Formula

a(n) = A046523(n^2) = A046523(n)^2.
a(n) = A278259(2*n).

A278162 Least number with the prime signature of n^2 + 1.

Original entry on oeis.org

1, 2, 2, 6, 2, 6, 2, 12, 6, 6, 2, 6, 6, 30, 2, 6, 2, 30, 12, 6, 2, 30, 6, 30, 2, 6, 2, 30, 6, 6, 6, 30, 12, 30, 6, 6, 2, 30, 12, 6, 2, 12, 6, 60, 6, 6, 6, 210, 6, 6, 6, 6, 6, 30, 2, 30, 2, 120, 6, 6, 6, 6, 6, 30, 6, 6, 2, 30, 24, 6, 12, 6, 30, 210, 2, 30, 6, 30, 6, 6, 6, 30, 12, 210, 2, 6, 6, 30, 6, 30, 2, 30, 6, 60, 2, 6, 6, 30, 30, 60, 6, 6, 6, 30, 6, 30, 6
Offset: 0

Views

Author

Antti Karttunen, Nov 19 2016

Keywords

Crossrefs

Bisection of A278260.
Cf. A005574 (positions of 2's), A085722 (of 6's).
Cf. also A278160, A278244, A278254.

Programs

  • Mathematica
    Table[Times @@ MapIndexed[(Prime@ First@ #2)^#1 &, #] &@ If[Length@ # == 1 && #[[1, 1]] == 1, {0}, Reverse@ Sort@ #[[All, -1]]] &@ FactorInteger[ n^2 + 1], {n, 0, 120}] (* Michael De Vlieger, Nov 21 2016 *)
  • PARI
    A046523(n) = my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]) \\ From Charles R Greathouse IV, Aug 17 2011
    A278162(n) = A046523((n^2)+1);
    for(n=0, 10000, write("b278162.txt", n, " ", A278162(n)));
    
  • Scheme
    (define (A278162 n) (A046523 (+ 1 (* n n))))

Formula

a(n) = A046523(A002522(n)) = A046523((n^2)+1).
a(n) = A278260(2*n).

A278497 a(n) = Least number with the prime signature of A276573(n).

Original entry on oeis.org

2, 6, 8, 2, 6, 16, 12, 6, 24, 8, 30, 32, 6, 6, 24, 2, 12, 48, 6, 2, 24, 2, 12, 64, 2, 30, 72, 12, 30, 48, 2, 6, 24, 60, 6, 96, 12, 30, 30, 72, 48, 6, 12, 120, 6, 60, 128, 2, 6, 24, 2, 6, 144, 12, 2, 24, 6, 6, 96, 48, 30, 120, 12, 2, 48, 2, 6, 30, 24, 192, 30, 60, 72, 6, 12, 210, 6, 216, 6, 6, 96, 2, 30, 2, 12, 240, 32, 12, 24, 2, 30, 256, 6, 12, 120, 6, 120
Offset: 1

Views

Author

Antti Karttunen, Nov 25 2016

Keywords

Crossrefs

Cf. A277014 (gives the indices of squares).
Cf. also A278232.

Programs

Formula

a(n) = A046523(A276573(n)).
For all n >= 1, a(A260733(1+n)) = A278160(n).
Showing 1-3 of 3 results.