A066124 - OEIS

A066124

In base 2, three 'Reverse and Add' steps are needed to reach a palindrome.

44, 50, 54, 58, 72, 92, 98, 118, 154, 156, 184, 194, 206, 214, 216, 234, 242, 272, 296, 316, 364, 376, 386, 406, 466, 470, 478, 502, 564, 566, 570, 572, 626, 628, 634, 688, 690, 696, 716, 732, 748, 752, 770, 790, 798, 806, 814, 820, 822, 824, 854, 870, 880

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

The analog of A065208 in base 2. The number of steps starts at 0, so palindromes (cf. A006995) are excluded.

LINKS

Harry J. Smith, Table of n, a(n) for n=1,...,1000

Index entries for sequences related to Reverse and Add!

PROG

(PARI) Rev(x)= { local(d, r=0); while (x>0, d=x%10; x\=10; r=r*10 + d); return(r) } digitsIn(x)= { local(d); if (x==0, return(1)); d=1 + log(x)\log(10); if (10^d == x, d++, if (10^(d-1) > x, d--)); return(d) } Palin(x)= { local(d, e, f, i, t, y); if (x==0, return(1)); y=x; d=digitsIn(x); t=10^(d - 1); for (i=1, d\2, f=y-10*(y\10); y\=10; e=x\t; x-=t*e; t/=10; if (e!=f, return(0)) ); return(1) } baseE(x, b)= { local(d, e=0, f=1); while (x>0, d=x-b*(x\b); x\=b; e+=d*f; f*=10); return(e) } baseI(x, b)= { local(d, e=0, f=1); while (x>0, d=x-10*(x\10); x\=10; e+=d*f; f*=b); return(e) } calcB(p)= { local(b, r); b=baseE(p, 2); r=Rev(b); d=baseI(r, 2) + p; b=baseE(d, 2); return(b); } { n=0; for (m=1, 10^9, d=m; t=1; b=baseE(d, 2); for (i=1, 3, if (Palin(b), t=0; break); b=calcB(d)); if (t && Palin(b), write("b066124.txt", n++, " ", m); if (n==1000, return)) ) } \\ Harry J. Smith, Feb 01 2010

CROSSREFS

Cf. A006995, A065208, A066122.

Sequence in context: A116355 A071318 A085651 * A270298 A231402 A116227

Adjacent sequences: A066121 A066122 A066123 * A066125 A066126 A066127

KEYWORD

base,nonn

AUTHOR

Klaus Brockhaus, Dec 08 2001

EXTENSIONS

OFFSET changed from 0,1 to 1,1 by Harry J. Smith, Feb 01 2010

STATUS

approved