A071844 - OEIS

A071844

Numbers k such that reverse(gpf(k)) = gpf(k+1), where gpf(n) = A006530(n); a(1)=1.

1, 73, 155, 425, 650, 1053, 1243, 1364, 1632, 1859, 1988, 2133, 2774, 4046, 4991, 5328, 5475, 5529, 6292, 8029, 8176, 10730, 12495, 13431, 17459, 17576, 17879, 18980, 20329, 20855, 20944, 22815, 24024, 25122, 26936, 28518, 29319, 29784

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..38.

EXAMPLE

29319 is a term because 29319 = 3*29*337 and 29320 = 2*2*2*5*733.

MATHEMATICA

p =(FactorInteger@#)[[-1, 1]] & /@ Range@(10^6); Prepend[Flatten@Position[Transpose[{Most@p, IntegerReverse@Rest@p}], {a_, a_}], 1] (* Hans Rudolf Widmer, Jun 02 2024 *)

PROG

(PARI) gpf(k) = vecmax(factor(k)[, 1]); \\ A006530

isok(k) = (k==1) || fromdigits(Vecrev(digits(gpf(k)))) == gpf(k+1); \\ Michel Marcus, Jun 02 2024

CROSSREFS

Cf. A004086, A006530.

Sequence in context: A044324 A044705 A248399 * A078856 A142326 A142377

Adjacent sequences: A071841 A071842 A071843 * A071845 A071846 A071847

KEYWORD

base,nonn

AUTHOR

Jason Earls, Jun 08 2002

STATUS

approved