A083793 Numbers n such that n and n-1 have the same prime signature. Numbers not included in A083792.

3, 15, 22, 34, 35, 39, 45, 58, 76, 86, 87, 94, 95, 99, 117, 119, 123, 134, 136, 142, 143, 146, 148, 159, 172, 178, 202, 203, 206, 214, 215, 218, 219, 231, 245, 254, 286, 297, 299, 302, 303, 327, 333, 335, 376, 382, 388, 394, 395, 430, 435, 446, 447, 454, 482

Offset

1,1

Links

Alois P. Heinz, Table of n, a(n) for n = 1..20000

Maple

s:= n-> sort(map(i-> i[2], ifactors(n)[2])):
a:= proc(n) option remember; local k; for k from
      1+a(n-1) while s(k)<>s(k-1) do od; k
    end: a(0):=1:
seq(a(n), n=1..60);  # Alois P. Heinz, Mar 09 2018

Mathematica

PrimeFactorExponents[n_] := Flatten[ Table[ # [[2]], {1}] & /@ FactorInteger[n]]; Select[ Range[3, 543], PrimeFactorExponents[ # ] == PrimeFactorExponents[ # - 1] & ]

Crossrefs

Cf. A083792.

Sequence in context: A009057 A289712 A083795 * A324127 A083934 A072200

Adjacent sequences: A083790 A083791 A083792 * A083794 A083795 A083796

Keyword

nonn

Author

Amarnath Murthy, May 07 2003

Extensions

Corrected and extended by James A. Sellers, May 19, 2003

Some terms corrected by Alois P. Heinz, Mar 09 2018

Status

approved