Dear Richard and Seqfans, A005178 is periodic modulo 30 (pay attention that start from 0 not 1): %C A005178 congruent to 0 mod 100 if n is congruent to 14 or 29 mod 30 %C A005178 congruent to 1 mod 100 if n is congruent to 0 or 1 or 12 or 16 or 27 or 28 mod 30 %C A005178 congruent to 5 mod 100 if n is congruent to 2 or 11 or 17 or 26 mod 30 %C A005178 congruent to 11 mod 100 if n is congruent to 3 or 25 mod 30 %C A005178 congruent to 36 mod 100 if n is congruent to 4 or 9 or 19 or 24 mod 30 %C A005178 congruent to 45 mod 100 if n is congruent to 8 or 20 mod 30 %C A005178 congruent to 51 mod 100 if n is congruent to 13 or 15 mod 30 %C A005178 congruent to 61 mod 100 if n is congruent to 10 or 18 mod 30 %C A005178 congruent to 81 mod 100 if n is congruent to 6 or 7 or 21 or 22 mod 30 %C A005178 congruent to 95 mod 100 if n is congruent to 5 or 23 mod 30 Together 10 different rests modulo 30. Best wishes Artur