A256361 Numbers that are multiple-digit narcissistic numbers in exactly two bases.

17, 28, 29, 45, 50, 85, 126, 133, 136, 145, 153, 160, 200, 245, 250, 260, 261, 265, 353, 365, 371, 405, 425, 442, 450, 490, 514, 520, 533, 585, 605, 650, 666, 680, 738, 800, 855, 925, 936, 1000, 1025, 1105, 1225, 1233, 1250, 1280

Offset

1,1

Links

Tim Johannes Ohrtmann, Table of n, a(n) for n = 1..3541

W. Schneider, Perfect Digital Invariants: Pluperfect Digital Invariants(PPDIs)

Eric Weisstein's World of Mathematics, Narcissistic Number

Wikipedia, Narcissistic number

Example

a(1) = 17 because this is the first number that is a multiple-digit narcissistic number in exactly two bases (3 and 13).

Prog

(PARI) for(n=3, 1000000, k=0; for(z=2, n, y=n; j=0; L=List(); until(y==0, x=y%z; j++; listinsert(L, x, j); while(!((y%z)==0), y--); y=y/z); t=0; for(p=1, j, t+=L[p]^j); if(n==t, k++)); if(k==2, print1(n, ", ")))

Crossrefs

Cf. A005188.

Cf. A256359 (every number of bases).

Cf. A256360, A256362, A256363, A256364, A256365 (1, 3 to 6 bases).

Cf. A256459 (first occurrences).

Sequence in context: A147218 A146856 A217409 * A293927 A269307 A364555

Adjacent sequences: A256358 A256359 A256360 * A256362 A256363 A256364

Keyword

nonn,base

Author

Tim Johannes Ohrtmann, Mar 26 2015

Status

approved