A044028 Numbers k such that 4 and 7 occur juxtaposed in the base-10 representation of k but not of k+1.

47, 74, 147, 174, 247, 274, 347, 374, 447, 479, 547, 574, 647, 674, 749, 774, 847, 874, 947, 974, 1047, 1074, 1147, 1174, 1247, 1274, 1347, 1374, 1447, 1479, 1547, 1574, 1647, 1674, 1749, 1774, 1847, 1874, 1947, 1974, 2047

Offset

1,1

Links

Table of n, a(n) for n=1..41.

Mathematica

okQ[n_]:=Module[{sidn=Sort/@Partition[IntegerDigits[n], 2, 1]}, MemberQ[sidn, {4, 7}]]; Select[Range[2100], okQ[#]&&!okQ[#+1]&] (* Harvey P. Dale, Feb 14 2012 *)

Crossrefs

Sequence in context: A165335 A039425 A043248 * A126095 A132259 A046002

Adjacent sequences: A044025 A044026 A044027 * A044029 A044030 A044031

Keyword

nonn,base

Author

Clark Kimberling

Status

approved