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A066122 In base 2, one 'Reverse and Add' step is needed to reach a palindrome. 12
2, 4, 6, 8, 10, 12, 14, 16, 18, 24, 30, 32, 34, 36, 38, 40, 42, 48, 52, 56, 62, 64, 66, 68, 70, 80, 82, 96, 100, 102, 112, 114, 126, 128, 130, 132, 134, 136, 138, 140, 142, 144, 146, 148, 150, 160, 162, 168, 170, 176, 178, 192, 196, 198, 200, 204, 208, 212, 224 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The analog of A065206 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

(ARIBAS): function b2revadd_steps(k, stop: integer); var c, n, m, steps, rev: integer; begin n := 0; c := 0; while c < stop do m := n; rev := b2reverse(m); steps := 0; while steps < k and m <> rev do m := m + rev; rev := b2reverse(m); inc(steps); end; if steps = k and m = rev then write(n, " "); inc(c); end; inc(n); end; end; b2revadd_steps(1, 66).

(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) } { n=0; for (m=1, 10^9, b=baseE(m, 2); r=Rev(b); d=baseI(r, 2) + m; b=baseE(d, 2); if (Palin(b), write("b066122.txt", n++, " ", m); if (n==1000, return)) ) } \\ Harry J. Smith, Feb 01 2010

CROSSREFS

Cf. A006995, A065206.

Sequence in context: A276128 A309239 A152966 * A119766 A030143 A110725

Adjacent sequences:  A066119 A066120 A066121 * A066123 A066124 A066125

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

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Last modified April 13 15:11 EDT 2021. Contains 342936 sequences. (Running on oeis4.)