1,2

Recall that P(n) = n(3n-1)/2. From the fifth term on, it appears that all terms of the sequence begin with "666". :-)

P_5(67) = 6700, beginning in 67. Hence 67 is a term of the sequence.

(*returns true if a begins with b, false o.w.*) f[a_, b_] := Module[{c, d, e, g, h, i, r}, r = False; c = ToString[a]; d = ToString[b]; g = StringPosition[c, d]; h = Length[g]; If[h > 0, i = g[[h]]; If[i[[1]] == 1, r = True]]; r]; Do[If[f[n(3n - 1)/2, n], Print[n]], {n, 1, 10^6} ]

Sequence in context: A139910 A077789 A124291 this_sequence A073552 A036948 A020469

Adjacent sequences: A067272 A067273 A067274 this_sequence A067276 A067277 A067278

base,nonn

Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Feb 21 2002