A299987 Lexicographic first sequence of nonnegative integers such that a(n) + a(n+1) has a digit 7, and no term occurs twice.

0, 7, 10, 17, 20, 27, 30, 37, 33, 4, 3, 14, 13, 24, 23, 34, 36, 1, 6, 11, 16, 21, 26, 31, 39, 8, 9, 18, 19, 28, 29, 38, 32, 5, 2, 15, 12, 25, 22, 35, 40, 47, 50, 57, 60, 67, 70, 77, 80, 87, 83, 44, 43, 54, 53, 64, 63, 74, 73, 84, 86, 41, 46, 51, 56, 61, 66, 71, 76, 81, 89, 48, 49, 58, 59, 68, 69, 78, 79, 88, 82, 45, 42, 55, 52, 65, 62, 75, 72, 85, 90

Offset

0,2

Comments

A permutation of the nonnegative integers.

Links

Table of n, a(n) for n=0..90.

Prog

(PARI) a(n, f=1, d=7, a=0, u=[a])={for(n=1, n, f&&if(f==1, print1(a", "), write(f, n-1, " "a)); for(k=u[1]+1, oo, setsearch(u, k)&&next; setsearch(Set(digits(a+k)), d)&&(a=k)&&break); u=setunion(u, [a]); u[2]==u[1]+1&&u=u[^1]); a}

Crossrefs

Cf. A299977 (analog with positive terms), A299957 (analog with digit 1), A299970, A299982..A299988, A299969 (digit 0, 2..8, 9).

Sequence in context: A218128 A175666 A299997 * A192273 A098748 A020692

Adjacent sequences: A299984 A299985 A299986 * A299988 A299989 A299990

Keyword

nonn,base

Author

M. F. Hasler and Eric Angelini, Feb 22 2018

Status

approved